Added field for range usage in range model
Added range usage to the display, range usage updates in ranges save method
Merge branch 'master' of https://github.com/OSU-Net/cyder into Range_Usage

Conflicts:
	cyder/cydhcp/range/models.py
Missed a part of the merge
Static Interface now updates range usage
Only save range if it exists
If range usage does not exist, do not display
Use get model to avoid import recusion
Update range usage on create/delete of ptr
Update range usage on create/delete of a record
Renamed range usage migration
Added logic for calculating dynamic range usage
Edited Range detail view to vary depending on range_type
Merge with master to avoid migration conflicts
Merge branch 'master' of https://github.com/OSU-Net/cyder into Range_Usage
Removed . from system create url regex
Modified range detail view to handle dynamic and static ranges seperately
Prepare ptrs,ranges,dynamic and static intrs, a records for migrations
Fixed extra _ in kwargs
Migrations almost complete, some range usage is being calculated when it shouldn't though