add created_at in WQL+status
add created_at in WQL+priority
add created_at in WQL+tag
- created_at is not available in WQL.
- If possible, user can specify the start and end created time as a criteria in url for the search results as it is not convenient to keep changing the date range in WQL. like http://wagn.org/Wagn_1_14+open_tickets?start=20140924000000&end=20140924230000