Aggregate all liquidity restrictions in a single place (#1921)

* Clean up session key rotation

* Fix build

* Bump version

* Introduce feature to balances.

* Move staking locking logic over to central point

* ^^^ rest

* First part of assimilation

* More assimilation

* More assimilation

* Fix most tests

* Fix build

* Move Balances to new locking system

* :q!

* Bump runtime version

* Build runtime

* Convenience function

* Test fix.

* Whitespace

* Improve type legibility.

* Fix comment.

* More tests.

* More tests.

* Bump version

* Caps

* Whitespace

* Whitespace

* Remove unneeded function.

substrate/core/primitives/Cargo.toml

@@ -8,7 +8,7 @@ edition = "2018"
 rstd = { package = "sr-std", path = "../sr-std", default-features = false }
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
 rustc-hex = { version = "2.0", default-features = false }
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 twox-hash = { version = "1.1.0", optional = true }
 byteorder = { version = "1.1", default-features = false }
@@ -46,7 +46,7 @@ std = [
 	"hash256-std-hasher/std",
 	"hash-db/std",
 	"rstd/std",
-	"serde/std",
+	"serde",
 	"rustc-hex/std",
 	"twox-hash",
 	"blake2-rfc",