Introduce 128-bit shim for u128/i128 and use it for Balance (#163)

* Add 128-bit shim and use for balance.

* Fix tests.

* Fix wasm build.

polkadot/runtime/wasm/Cargo.lock

@@ -159,7 +159,7 @@ dependencies = [
 [[package]]
 name = "integer-sqrt"
 version = "0.1.0"
-source = "git+https://github.com/paritytech/integer-sqrt-rs.git#f4cf61482096dc98c1273f46a10849d182b4c23c"
+source = "git+https://github.com/paritytech/integer-sqrt-rs.git#886e9cb983c46498003878afe965d55caa762025"
 
 [[package]]
 name = "keccak-hash"
@@ -214,7 +214,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "num-traits"
-version = "0.2.2"
+version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -618,7 +618,7 @@ name = "substrate-runtime-primitives"
 version = "0.1.0"
 dependencies = [
  "integer-sqrt 0.1.0 (git+https://github.com/paritytech/integer-sqrt-rs.git)",
- "num-traits 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.27 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_derive 1.0.27 (registry+https://github.com/rust-lang/crates.io-index)",
  "substrate-codec 0.1.0",
@@ -863,7 +863,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)" = "89f010e843f2b1a31dbd316b3b8d443758bc634bed37aabade59c686d644e0a2"
 "checksum memory_units 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "71d96e3f3c0b6325d8ccd83c33b28acb183edcb6c67938ba104ec546854b0882"
 "checksum nodrop 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)" = "9a2228dca57108069a5262f2ed8bd2e82496d2e074a06d1ccc7ce1687b6ae0a2"
-"checksum num-traits 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "dee092fcdf725aee04dd7da1d21debff559237d49ef1cb3e69bcb8ece44c7364"
+"checksum num-traits 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)" = "775393e285254d2f5004596d69bb8bc1149754570dcc08cf30cabeba67955e28"
 "checksum num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c51a3322e4bca9d212ad9a158a02abc6934d005490c054a2778df73a70aa0a30"
 "checksum owning_ref 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "cdf84f41639e037b484f93433aa3897863b561ed65c6e59c7073d7c561710f37"
 "checksum parity-wasm 0.27.6 (registry+https://github.com/rust-lang/crates.io-index)" = "bd4dc02a80a0315b109e48992c46942c79bcdb8fac416dd575d330ed9ced6cbd"