modifications to fix tests since changing window handles to tlbcs; fixes...

... 29

This gets tests passing again, but doesn't integrate window switching/handling with our ui libraries nicely at all. I'm thinking we could have something like "find_opened_window()" in the browser class or a neighboring class that would return the new window handle when taking an action that results in a window opening to avoid the tedious pattern I have here. @whimboo, what do you think?
Please keep `self.marionette`. We might also want to update the libs to get rid of `client`, which is IMHO not that understandable. I would vote for consistency.