Update travis config

[sashadev-sky]

Fixes #625 (<=== Add issue number here)

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[gitpod-io]

[sashadev-sky]

@jywarren @VladimirMikulic a few optimizations here... npm run build already runs our tests so we don't need to run grunt test as well (we were running specs twice before).

Also, I set browserDisconnectTolerance: 5. This means it will retry 5 times if it disconnects. This should prevent the builds from failing.

Will look into further optimizations suggested by @jywarren in other PRs