feat(testing): run end to end tests on firefox and safari as well as chrome

Update the Travis and Jenkins configs to run protractor tests on Safari and Firefox as well,
and make the Travis tests run output XML and turn off color.

Fix tests which were failing in Firefox due to clear() not working as expected.

Fix tests which were failing in Safari due to SafariDriver not understanding the minus key,
and disable tests which SafariDriver has no support for.
refactor(testing): run end to end tests on separate browsers in parallel.