Added user accounts.

Used devise gem to enable user account creation.
Minor styling added, login features not added yet.
Added links to login with verification, and sign out
More styling, nav bar class
added message for no cats
Created redirect if user visits new page while not logged in, added rspec test
Fixed user_signed_in? on index page
resloved merge issues
fixed tests, and index html
fixed my sloppy spaces
adjusted test
Merge pull request #6 from LaunchAcademy/no_cats

User Verification, no cats and more