[#1767] Fix bug with send_email_notifications not working with paster

The problem is that our validators notice that .send_email_notifications()
didn't call its auth functions and raise an Exception. But it shouldn't call
it's auth functions when being called with paster anyway, so it's correct.

This fixes that.
Use assert_raises instead of the full nose.tools.assert_raises
Merge branch 'master' into 1767-send-email-notifications-with-paster

Conflicts:
	ckan/new_tests/logic/action/test_update.py
Merge branch '1767-send-email-notifications-with-paster'