Adds and removes fixed class from navbar on scroll
Merges listing styles with up to date development branch
Adds message user modal
Merge branch 'development' of https://github.com/felguerez/aircycle into messages

Conflicts:
	web/app/views/listings/show.html.erb
adds message modal that uses the create message usecase
Adds in memory database methods and tests for getting all messages and unread messages for a user
Adds orm db methods that return unread messages and all messages for a user
Notifies users if they have unread mail in their inbox
Adds a basic inbox view
Adds column 'create_at' to messages table.
Adds styling to the messages inbox view.
Adds javascript and html for tabbing between inbox and sentbox. Styles the messages view.
adds message_thread entity, model, table, and adds column to messages table
Adds inmemory db methods for creating method threads and returning an array of messages given a message_thread_id
adds orm methods for creating message threads and getting messages by message thread id
Adds usecase for creating a message thread
Updates usecase for creating a message
Updates messages view
Fixes problems with #create_message in the orm database
fixes sass error
fixes js asset pipeline
styles log in modal
Completes the 'Add Listing' 'user story' on the front-end.
-> User can now:
1. Create listing
2. Add photos to listing
3. Change listing attributes
4. Submit finalized listing