[DESIRED CAPABILITIES]
- Add a desired_capabilities option that provides full control over the desiredCapability object
- Add a new_from_caps constructor to distinguish against the normal new constructor
- Add a ua option to allow injection of LWP::UserAgent for testing
[MOO REWRITE]
- Completed the Moo restructure (pr #103) with pr #122, fixing a bug in _check_ok (#121).