Updated the license.
#19: invoice workflow.
Invoice default status set to draft.
Fixing the tests.
Models refactoring.
Added Estimate models.
#5: Added the estimate factories.
Use kwargs in the tests reverse.
#29: added the estimate's forms.
#29: Refactored the views for estimate views.
#29: Added the estimate templates.
#29: Added the urls for estimates.
#11: Prepare the buttons to accept or refuse an estimate.
Merge pull request #30 from linovia/develop

Merge develop into master