Nicer style for the invoice list.
Added estimates to the admin.
Added the user management app to the tests.
Include lxml for the tests.
Estimates approval.
Simplier password hashers.
Added is_draft to the model.
Added the estimate validation and estimate status change views.
Tests for the estimate workflow.
Added the estimate menu entry.
Updated the template for the estimate workflow.
Merge remote-tracking branch 'origin/develop'