Convert unnecessary storage item to static. (#3093)

* Convert unnecessary storage item to static.

* Polish

* 6 second blocks.

* Compile fixes

* Bump runtime

* Fix

* Another fix

* Import `srml_support::traits::Get`

* Export MinimumPeriod from `decl_module!`

* Remove `config` from Timestamp

* Clean up warnings

substrate/node/executor/src/lib.rs

@@ -346,7 +346,6 @@ mod tests {
 			collective_Instance1: Some(Default::default()),
 			collective_Instance2: Some(Default::default()),
 			elections: Some(Default::default()),
-			timestamp: Some(Default::default()),
 			contracts: Some(ContractsConfig {
 				current_schedule: Default::default(),
 				gas_price: 1 * MILLICENTS,