chore(karma): use karma 0.12.31 instead of a custom fork

Previously Vojta set us up to use a custom fork of Karma that used socket.io 1.3.4. This change moves us to an official release of Karma but downgrades socket.io back to 0.9.16.

We now need to hurry up and finish the socket.io upgrade in karma which was blocked on shrinkwrap issues in Angular that are resolved with the previous few commits in this PR.

Author: IgorMinar