testing link in learn section
add area code to phone number, clean some related styling
add area code to maost feedback page
revise styling
re-style message annotation across site
Make null phone number interpolation work on subject page
Expand test coverage for messages
Merge pull request #165 from codeforamerica/expand-message-test-coverage

Expand test coverage for messages
Rename Subject to Location.
Rename FeedbackInput to Answer
Merge pull request #166 from codeforamerica/rename-tables-for-clarity

Rename domain objects for clarity
Add Location#has_voice_messages? and #has_numerical_responses?
Use Location#has_numerical_responses? in LocationController
Add NotificationSubscription.confirmed/.with_new_answers/#newest_ansewrs
Associate Answer with NotificationSubscription
Refactor Notifier
adding rails email preview gem and removing letter opener gem
Refactor NotificationSubscription#confirmation_sent?
Rename weekly_activity2 mailer to weekly_activity
Rename Notifier to SubscriberNotifier