Use connection_pool for Travis::Features.
Add a Redis connection pool.
Revert "Use connection_pool for Travis::Features."

This reverts commit 5d4bc98545d838f32de6950db39d1c512278f6f3.
We use a direct pool proxy instead, so the original code can remain
unchanged.
Use the RedisPool instead of the Redis client.
Add tests for RedisPool.
Merge branch 'master' into mm-connection-pool-features
Merge branch 'master' into mm-connection-pool-features
Add index to builds.state
Use the state to filter out unstarted builds

This should speed up the query, since there is now an index on
builds.state.
Dump schema
Change Travis.config.env to Travis.env
Remove old columns from job and build

- Remove compatibility code for status and result from build
- Remove compatibility code for status from job
- Change code using symbols for state to use strings
- Adding migrations to change jobs and builds with state "finished"
- Remove unused columns from job and build
Don't denormalize the language key on builds

This was removed from the database, and is not being used.
Submit metrics queue.
Rescue errors triggering job notifications.

Depending on the scenario this could cause a lot of exception
back traces to be logged, clogging our logs. To keep track of the
errors it adds a metric.
Merge pull request #213 from travis-ci/mm-rescue-log-update

Rescue errors triggering job notifications when writing logs
Mark builds and jobs with NULL results as errored

Looked through the database and the only jobs/builds matching this are
jobs from before we added error states, but where the worker would error
and spew out an exception in the log.

For example: https://travis-ci.org/svenfuchs/globalize3/jobs/849524
Remove status fields from the factories
Remove builds.recent from find_builds

The behaviour was changed in 73782013c0585f6de5be159b33905b8ab0146e56,
and this is the only place where that scope is still used.
Build#older_than already handles the number being nil, so we can just
remove the entire conditional around that.
Merge pull request #212 from travis-ci/hh-remove-old-builds-and-jobs-columns

Remove old columns from job and build