fixed the date in the graphs
fixed group.add_phone_numbers_to_group method to accept arrays as well as strings.
added test for changes to group.add_phone_numbers method.
added method to return recipients for a given group. Also added test.
working on tests for new notifier
updated notifier. updated tests.
fixing merge conflicts
Merge branch 'develop' of https://github.com/codeforamerica/promptly into develop