* added task union repeat query
* converted one of the queries to use the new union query
* fixed null pointer bugs
* TaskTable#getColumns now accept null arguments
[refactoring] added static import to columns
* now using new table to get due alarms
* fixed bug where separator couldn't be used as a regular expression
* fixed bug with CONTENT_URI
* fixed bug with get due tasks query
* [testing] added new unit test
* fixed bug in get due query