Run travis tests on Microsoft Edge

[Narretz]

• update to karma 0.13.x (Edge poses as webkit browser, confusing karma)
• ~~install a launcher for Edge? See issue: https://github.com/karma-runner/karma-ie-launcher~~/issues/35
• update karma conf
• update travis build.sh

[petebacondarwin]

Possibly use https://github.com/nicolasmccurdy/karma-edge-launcher ?

[mgol]

A separate Edge launcher would only be needed to run tests locally, similarly to how karma-chrome-launcher & karma-firefox-launcher are needed only for that. For Travis purposes karma-sauce-launcher for Sauce Labs & karma-browserstack-launcher for BrowserStack are enough. Therefore, I think the second point is invalid.

[Narretz]

PR here #14401, but needs some work