Travis improvements

[eschkufz]

Overview

Travis scripts are working correctly now, but incorrectly returning failed because coverage times out (all tests on all targets are running correctly). Increase the timeout on coverage and only run coverage on pull requests --- coverage looks like it takes about an hour and we don't want it triggering on every single branch commit. Travis also supports a configuration which will automatically cancel all but the most recent set of tests, let's make sure that's turned on.

Deliverables

• Improve travis settings