added twitter sign-in button to front page
modified front page's title and description box
placed end date label in its own li element
added a link to get back to a user's challenges
added uniform width to form input fields and reverted to standard font family in form
added a helper method for displaying the date
styled acceptance, rejection, and concede buttons the same as the others
added tweet upon challenge reject/accept and status update on challenge after concession
removed local db username and password
revising rspec tests due to addition of tweet action in response
Merge pull request #27 from KevinFalank/css2

CSS changes and tweaks and tweet and response update