Chainspec validation (#6197)

* chainspec validation

* better error formatting for chainspec

* lint validate_chainspecs.sh

* quit takes &str instead of S: AsRef<str>

* push CI

* don't double check spec validity

scripts/validate_chainspecs.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+ERR=0
+cargo build --release -p chainspec
+
+for spec in ethcore/res/*.json; do
+    if ! ./target/release/chainspec "$spec"; then ERR=1; fi
+done
+
+for spec in ethcore/res/ethereum/*.json; do
+    if ! ./target/release/chainspec "$spec"; then ERR=1; fi
+done
+
+exit $ERR
+