Fix bug in create method for user class

Now correctly pulls oauth token and secret for current user
Add simple_form to Gemfile
Gemfile.lock
Create form for posting to twitter via modal
Create simple_form files
Modify tweeter instance method
Create form for post_to_twitter modal
Add post_to_twitter method to dashboard_controller.rb
Merge pull request #4 from mattThousand/set_env_vars

Set env vars