chore(travis): implement continuous integration strategy using Travis-CI

It may unfortunately be necessary to cut back and rely on browsers available on Travis, but I'm hoping
this is not the case.

Closes #13
chore(travis): build logs dir (used by SL scripts)

I omitted these initially, but it would take effort to find a way to make this work without the
logging.
chore(dependencies): install karma-sauce-launcher on TravisCI

Self-explanatory change, the sauce launcher is required to launch these browsers on the CI server.
chore(karma): add IE* custom browsers for CI

These will be removed if they are too expensive (or if anyone tells me to!), but ideally this library
should support IE9.
chore(travis): use LOG_INFO rather than LOG_DEBUG for karma logLevel

There is a bit too much spammy output on Travis, this can be disabled for now.