Allow querying for runs by date range

e.g. /runs/date/from/2013-10-01/to/2013-11-01/
Returns runs scheduled between 2013-10-01_00:00:00 and
2013-11-01_23:59:59
Put date-filter tests in their own class

Also add tests for error cases
Remove debug statement
Merge pull request #31 from ceph/daterange

Allow querying for runs by date range