Correct log index in transaction receipt (#3995)

* Moving logs to separate, testable function

* Adding test

* Fixing log index

* Adding transaction log index

* Fixing rpc tests

* Making interface of  a bit cleaner.

ethcore/src/tests/client.rs

@@ -320,4 +320,3 @@ fn does_not_propagate_delayed_transactions() {
 	assert_eq!(2, client.ready_transactions().len());
 	assert_eq!(2, client.miner().pending_transactions().len());
 }
-