patch functions only work as context managers

[blaix]

The tdubs patch functions are just pass throughs to python's mock.patch, but I don't know if all the supported arguments to that work with tdubs doubles, and I haven't tested them as decorators or using start/stop

[blaix]

My naive initial implementation only works as a context manager. There's a lot more work to do to make it work as a class or function decorator (dang).

Need to decide: update docs to explicitly only support using patch as a context manager, or do the work to make it work just like python's patch?

[blaix]

I'm just going to remove it and go back to the old method of saying pass a tdubs object as the new value on unittest's patch.