Replace --interactive by --action.

* bzrlib/tests/test_conflicts.py:
Switch from --interactive to --action.

* bzrlib/tests/blackbox/test_conflicts.py:
(TestResolve): Delete the --interactive tests.

* bzrlib/conflicts.py:
(cmd_resolve.run): Add an 'action' parameter. Refactor to clarify
what action is executed when. Get rid of the --interactive attempt.
(resolve): Add an 'action' parameter. Refactor to make the
conflict deletion depends on the resolution success.
(_resolve_interactive): Deleted.
(ConflictList.remove_files): Use conflict.cleanup()
(Conflict._do): Helper to execute an arbitratry resolution action.
(Conflict.cleanup, Conflict.done, Conflict.keep_mine,
Conflict.take_their): Declare the abstract methods.
(PathConflict.cleanup, PathConflict.done): Do-nothing
implementations.
(ContentsConflict.cleanup): Specific cleanup (strange).
(TextConflict.cleanup): Specific cleanup.
(HandledConflict.done, HandledConflict.cleanup): Do nothing
implementations.
(UnversionedParent.keep_mine, UnversionedParent.take_their): Hmm,
forced do-nothing implementations, something weird is going on
here.