* Move client DB opening logic to CLI

* Move restoration db open logic to CLI

This adds KeyValueDBHandler which handles opening a new database, thus allow us to move the restoration db open logic
out of ethcore.

* Move rocksdb's compactionprofile conversion to CLI

* Move kvdb_rocksdb as test dependency for ethcore

* Fix tests due to interface change

* Fix service tests

* Remove unused migration dep for ethcore

* ethcore test::helpers cleanup

* ethcore-service