Remove deprecated calls to the legacy transaction API.
Initial work for #537.
Merge branch 'master' into feature/deploy_with_extensions

Conflicts:
	modoboa/core/commands/deploy.py
Enable all extensions for testing.

see #537
Fixes.

see #585
Few fixes.

see #537
Merge branch 'master' into feature/deploy_with_extensions
Python 2.6 compat.

see #537
Merge branch 'master' into refactoring/django16

Conflicts:
	modoboa/extensions/admin/views/domain.py
	modoboa/extensions/admin/views/identity.py
Fix minor CSS issues and required django 1.6.