added test for binary tiddlers
added gamut tests

adapted from tiddlywebplugins.sqlalchemy as of 2012-12-16:
https://github.com/cdent/tiddlywebplugins.sqlalchemy/blob/c6418fc57a6b19f4b57193cefc3b0e301919d3d9/test/test_gamut.py
(various adjustments regarding handling of tiddler revisions, binary
tiddlers, and side effects - plus retained NoBagError in
list_tiddler_reivisions if appropriate)