chore: run more browsers on Travis (IE8,IE9,IE10,Safari,FF)

Also instead of running everything in parallel, there are only two parallel tasks:
- e2e tests running in the background (only on Chrome)
- all the unit tests running sequentially
chore: use only polling on Travis/SL
chore(travis): clean up logs

Forward SauceConnect logs and Karma debug logs into a file and print these files at the very end of a build.