* Implement runtime version checks in `set_code`

Check that the new runtime code given to `set_code` fullfills some
requirements:

- `spec_name` matches
- `spec_version` does not decreases
- `impl_version` does not decreases
- Either `spec_version` and `impl_version` increase

* Make tests almost work

* Some fixes after master merge

* Fix tests

* Add missed file

* Make depedency check happy?

* Remove leftover `sc-executor`

* AHHHHH

* Reset debug stuff

* Remove some 'static

* More 'static

* Some docs

* Update `Cargo.lock`