smart super_user queue routing

if a user specifies:

super_user: false

in their .travis.yml then we can route them to a different queue where super user (sudo access) is disabled
Merge branch 'master' into super_user_queue_detection
make the super_user check featureflippable
Merge pull request #380 from travis-ci/super_user_queue_detection

Super user queue detection
no super user?
Merge branch 'master' of github.com:travis-ci/travis-core
use sudo instead of super_user in the .travis.yml
use sudo, not super_user
bump the build
fix an issue with the postgres switcher, for now
echo the path
export the PATH again, odd
remove the path fixes
use the latest 2.0.x and 2.1.x mri ruby for testing
2.0 needs to be quoted for the UI to display it correctly
WIP
Update travis-core to 3.2.19
Revert "WIP" (didn't notice that it's in master)

This reverts commit 2697aadd1850b65c417dc0c0c91266c25ffdc9de.
Track timings for job updates.

This gives us a bit more insight as to where time is spent when a
job is updated in hub. It breaks down into tracking the entire
update per event type, the notify method per event time and
propagation per event type, in the hope that this gives us a few
more clues as to where time is spent.
Use #update_column and #update_attributes for RemoveLog

As pointed out in https://github.com/travis-ci/travis-api/pull/122#issuecomment-48041880
`log.save!` might not be saving attributes correctly.
We are speculatively using `#update_column` and `#update_attributes`
to see if that solves the problem