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

ethcore/res/constructor.json

@@ -11,7 +11,6 @@
 		"networkID" : "0x2"
 	},
 	"genesis": {
-		"gasLimitBoundDivisor": "0x0400",
 		"seal": {
 			"generic": "0x"
 		},

ethcore/res/validator_safe_contract.json

@@ -3,7 +3,6 @@
 	"engine": {
 		"basicAuthority": {
 			"params": {
-				"gasLimitBoundDivisor": "0x0400",
 				"durationLimit": "0x0d",
 				"validators": {
 					"safeContract": "0x0000000000000000000000000000000000000005"