Added fields in the timesheet line module

*added selection type field
*created view for the model by inheriting timesheet line
Converted to blank
Merge conflicts Issues Resolved

Conflicts:
	timeline.py
Merge branch 'master' of github.com:tarunbhardwaj/project_billing
Modified Billing Type field

*Added context for the section field
*which passes selected value to the inherited field as default
Merge pull request #3 from simmianand/master

Applied changes in billing.py and timeline.py