* spec loading cleanup in progress

* changed engine field in json spec

* refactored engine params

* polishing spec loading refactor

* fixed compiling json tests

* fixed compiling parity

* removed warnings

* removed commented out code

* fixed failing test

* bringing back removed TODO in spec.

This reverts commit d330f0b7.

Conflicts:
	sync/src/transaction_queue.rs

Closes #179