Fix formatting errors in notifications module according to PEP8

Fixed the following format errors:
notifications/email.py:321:9: E201 whitespace after '('
notifications/email.py:321:9: E272 multiple spaces before keyword
notifications/email.py:322:9: E128 continuation line under-indented for visual indent

Testing Done:
Ran unit tests for notifications module, and ran pep8 again.

Reviewed at https://reviews.reviewboard.org/r/6632/