Downplay selenium a bit

It's really just an implementation detail for now
Bump to selenium-standalone 2.43.1-5
Use a build of sauce-connect-launcher that downloads sc during the install step.
Fixes #37 and #45.
Reference the sc log for better debugging. Closes #48
Much better support for browsers specified via command line and tasks.

You can easily focus on either local or remote browsers (or both!), and
as an added bonus, wct --help now exists.
Merge pull request #54 from Polymer/browsers

Much better support for browsers specified via command line and tasks.
Close #47
Make the flags stand out a bit more
v1.2.0
[wip]