fix(travis-ci): remove defunct "scheduler" branch

The "scheduler" branch was merged to master and travis-ci.org
doesn't need to test what isn't there.
fix(controller/tests): run coverage with "--timid" flag

Running controller tests through the venerable coverage.py tool
raises some errors during cleanup, as we seem to have dangling
PostgreSQL sessions. Adding the "--timid" flag works around this.

Fixes #727.