srml: grandpa: Pause/resume current authority set (#3068)

* grandpa: add pause/resume signals to runtime module

* grandpa: add tests for srml pause/resume transitions

* node: bump spec_version

* Apply suggestions from code review

* Update core/finality-grandpa/primitives/src/lib.rs

* Update core/finality-grandpa/primitives/src/lib.rs

substrate/node/runtime/src/lib.rs

@@ -69,7 +69,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	// and set impl_version to equal spec_version. If only runtime
 	// implementation changes and behavior does not, then leave spec_version as
 	// is and increment impl_version.
-	spec_version: 113,
+	spec_version: 114,
 	impl_version: 114,
 	apis: RUNTIME_API_VERSIONS,
 };