Allow state skipping for dependent encoding profiles

[jjeising]

Implements #160, supersedes #171.

We may additionally want to check if the ticket is currently in a skippable state and do not skip states in this case. This would happen if the user manually set the ticket to a skippable state (e.g. ticket is currently in checking).

@pegro Requested changes from #171 should be implemented, can you have a look?