Update travis-ci to use ruby 2.1.1
Merge pull request #76 from axilleas/ruby_travis

Update travis-ci to ruby 2.1.1
Relax polisher deps, gracefully fail if missing (rev 3)

Now polisher gem contains minimal runtime deps w/ mechanism
to catch runtime load errors. Components missing reqs will
not be accessible / calling methods on them will indicate
to install optional dependencies

Rebased against latest master