rosie copy: use single commit

Modify `rosie create` and `rosa svn-{pre,post}-commit` to allow a suite copy to
be a single commit.

Add `rosa svn-{pre,post}-commit` test battery. Address part of #78.

Move `rosa-svn-{pre,post}-commit` logic into `lib/python/rosie/svn_{pre,post}_commit.py`.

Fix `rosa svn-pre-commit` not failing when an author not in the suite's `access-list` is adding items to a suite's trunk.

Add tests for `rosie id` to ensure deleted suites do not cause a
miscount in latest and next.

Close #821.