Add badges, switch to concurrent full test runs, including Safari.

[ryan-roemer]

• Implements sauce badge from #25
• Use builder for various parallel helpers
• Parallelize karma RJS + Webpack tests
• Parallelize all Sauce tests
• Add in full tests for Safari. Fixes #5
• Cut Travis CI time down from about 5-6 minutes to 3-4 minutes

/cc @exogen

[exogen]

Nice! I'm migrating the huge script loader build matrix to use builder envs as well. Testing all those script loaders takes hours.

btw, size badges for files on npmcdn are now supported, like so: