CLI improvements & fixes (#4812)

These are a few changes I missed during the refactoring.

1. Initialization issue and boilerplate

    Most importantly: part of the `Configuration` initialization was done in `sc_cli::init`. This means the user can not benefit from this initialization boilerplate if they have multiple `Configuration` since `sc_cli::init` can only be called once.

2. Boilerplate for `VersionInfo` and `Configuration`

    I'm also answering to the critic of @bkchr on the initialization using version: https://github.com/paritytech/substrate/pull/4692/files/bea809d4c14a2ede953227ac885e3b3f9771c548#r372047238 This will allow initializing a `Configuration` and provide the version by default.

3. Loading the `chain_spec` explicitly

    In the past it was done automatically but in some cases we want to delay this. I moved the code to `Configuration.load_spec()` so it can be called later on. `chain_spec` can also be written directly to the `Configuration` without using this `load_spec` helper.

4. [deleted]

5. Fixing issue that prevents the user to override the port

    In the refactoring I introduced a bug by mistake that could potentially prevent the CLI user to override the ports if defaults where provided for these ports (only on cumulus).

6. Change task_executor from Box to Arc

    This is useful for cumulus where we have 2 nodes with 2 separate Configuration that need to spawn tasks to the same runtime.

7. Renamed TasksExecutorRequired to TaskExecutor

    For consistency.

This is related to https://github.com/paritytech/cumulus/issues/24

This is the continuation (and hopefully the end of) #4692

substrate/Cargo.lock

@@ -150,6 +150,19 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "assert_cmd"
+version = "0.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6283bac8dd7226470d491bc4737816fea4ca1fba7a2847f2e9097fd6bfb4624c"
+dependencies = [
+ "doc-comment",
+ "escargot",
+ "predicates",
+ "predicates-core",
+ "predicates-tree",
+]
+
 [[package]]
 name = "assert_matches"
 version = "1.3.0"
@@ -1227,6 +1240,18 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "escargot"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "74cf96bec282dcdb07099f7e31d9fed323bca9435a09aba7b6d99b7617bca96d"
+dependencies = [
+ "lazy_static",
+ "log 0.4.8",
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "evm"
 version = "0.14.2"
@@ -3318,10 +3343,24 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
+[[package]]
+name = "nix"
+version = "0.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50e4785f2c3b7589a0d0c1dd60285e1188adac4006e8abd6dd578e1567027363"
+dependencies = [
+ "bitflags",
+ "cc",
+ "cfg-if",
+ "libc",
+ "void",
+]
+
 [[package]]
 name = "node-cli"
 version = "2.0.0"
 dependencies = [
+ "assert_cmd",
  "browser-utils",
  "frame-support",
  "frame-system",
@@ -3329,6 +3368,7 @@ dependencies = [
  "hex-literal",
  "jsonrpc-core",
  "log 0.4.8",
+ "nix",
  "node-executor",
  "node-primitives",
  "node-rpc",
@@ -4816,6 +4856,32 @@ version = "0.2.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "74490b50b9fbe561ac330df47c08f3f33073d2d00c150f719147d7c54522fa1b"
 
+[[package]]
+name = "predicates"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a9bfe52247e5cc9b2f943682a85a5549fb9662245caf094504e69a2f03fe64d4"
+dependencies = [
+ "difference",
+ "predicates-core",
+]
+
+[[package]]
+name = "predicates-core"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "06075c3a3e92559ff8929e7a280684489ea27fe44805174c3ebd9328dcb37178"
+
+[[package]]
+name = "predicates-tree"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e63c4859013b38a76eca2414c64911fba30def9e3202ac461a2d22831220124"
+dependencies = [
+ "predicates-core",
+ "treeline",
+]
+
 [[package]]
 name = "pretty_assertions"
 version = "0.6.1"
@@ -8118,6 +8184,12 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "efd1f82c56340fdf16f2a953d7bda4f8fdffba13d93b00844c25572110b26079"
 
+[[package]]
+name = "treeline"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7f741b240f1a48843f9b8e0444fb55fb2a4ff67293b50a9179dfd5ea67f8d41"
+
 [[package]]
 name = "trie-bench"
 version = "0.19.0"
@@ -8204,7 +8276,7 @@ version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3bfd5b7557925ce778ff9b9ef90e3ade34c524b5ff10e239c69a42d546d2af56"
 dependencies = [
- "rand 0.3.23",
+ "rand 0.7.3",
 ]
 
 [[package]]