Finish moo transition (closes #103 and #121)

Hey @peroumal1,

I let this linger for too long and master diverged a bit more than I was ready to deal with. Rebasing or merging led to a bunch of conflicts even in places I didn't expect, like in S/R/Commands.pm, even though the second half of #103 was primarily for the T::S::R::D side.

So, I rebased the second half of the commits in #103 down to one commit and cherry picked that on to master as https://github.com/gempesaw/Selenium-Remote-Driver/commit/7697c4e2c600cb055b43b969fc28b751a549ec0c. That commit made a lot more sense to me, since the changes were primarily to T/S/R/Driver.pm and T/S/R/WebElement.pm, with a small addition to S/R/Driver.pm for the testing attribute. 

At this point, `dzil test` is passing for me on OS X, Linux, and Windows with no need to update the mocks, which is nice. Would you mind taking a look at the combined changes to verify that I resolved the conflicts correctly, or at least that everything makes sense at a glance? I'd really appreciate it a second set of eyes on this :)

Thanks a bunch!