fix: don't crash/terminate upon errors within chokidar

Handle errors from chokidar and route them to the console. Previously,
these unhandled errors (which are very common when editing in Visual
Studio) would cause karma to terminate and all browsers to vanish. Fixes
#959
chore(travis): add presubmit script

This script takes any presubmit-master/stable-xxx branch and if all the tests pass,
the presubmit branch is merged into master/stable and also pushed to NPM.
chore(travis): less verbose NPM
chore(scripts): add merge_pr
Merge branch 'pr-1020' into presubmit-stable-pr-1020
chore(travis): make 0.10 Node the first VM

We run the presubmit on the first VM, let's use 0.10, as it has newer NPM and hopefully should be better / more stable.
chore(presubmit): determine stable/master release
chore(presubmit): add some more todos