Add APIs for querying runs by branch and suite

Examples:
    /runs/branch/master/
    /runs/branch/master/suite/rados/
    /runs/suite/rados/
Fix branch_regex and suite_regex
get_jobs_by_description
Add branch and suite to Run json
Rewrite controllers
Add more tests
Subqueries
Fix subqueries
Store query in request.context

... instead of passing it around amongst controllers
Do all name parsing in one function
Add migration for Run.scheduled
Add tests for hyphenated branch and suite strings
Fix suite/branch parsing as best we can for now

Embed a list of current suites in ceph-qa-suite. We'll have to keep this
up-to-date until we can get a change into teuthology that will
explicitly submit the suite and branch names.
Merge pull request #26 from alfredodeza/compare_runs

Implement filtering runs by branch and/or suite