Initial: Offchain Workers (#1942)

* Refactor state-machine stuff.

* Fix tests.

* WiP

* WiP2

* Service support for offchain workers.

* Service support for offchain workers.

* Testing offchain worker.

* Initial version working.

* Pass side effects in call.

* Pass OffchainExt in context.

* Submit extrinsics to the pool.

* Support inherents.

* Insert to inherents pool.

* Inserting to the pool asynchronously.

* Add test to offchain worker.

* Implement convenience syntax for modules.

* Dispatching offchain worker through executive.

* Fix offchain test.

* Remove offchain worker from timestamp.

* Update Cargo.lock.

* Address review comments.

* Use latest patch version for futures.

* Add CLI parameter for offchain worker.

* Fix compilation.

* Fix test.

* Fix extrinsics format for tests.

* Fix RPC test.

* Bump spec version.

* Fix executive.

* Fix support macro.

* Address grumbles.

* Bump runtime

substrate/core/state-machine/src/basic.rs

@@ -24,6 +24,7 @@ use trie::trie_root;
 use primitives::storage::well_known_keys::{CHANGES_TRIE_CONFIG, CODE, HEAP_PAGES};
 use parity_codec::Encode;
 use super::{Externalities, OverlayedChanges};
+use log::warn;
 
 /// Simple HashMap-based Externalities impl.
 pub struct BasicExternalities {
@@ -151,6 +152,11 @@ impl<H: Hasher> Externalities<H> for BasicExternalities where H::Out: Ord + Heap
 	fn storage_changes_root(&mut self, _parent: H::Out, _parent_num: u64) -> Option<H::Out> {
 		None
 	}
+
+	fn submit_extrinsic(&mut self, _extrinsic: Vec<u8>) -> Result<(), ()> {
+		warn!("Call to submit_extrinsic without offchain externalities set.");
+		Err(())
+	}
 }
 
 #[cfg(test)]