Merge pull request #18 from kstradley/master

Generated challenges model & created associations with user
Rename column in Challenges table and update specs

The "type" column is now "descripton."
Change spec to use invalid_user object
Generate Champion model
Replace User's champion column with Champion model
Make twitter link more specific
Move link for `My Champion` inside session check

The user can't have a valid `my champion` link until they log in.
Autoload files in /lib
A champion belongs to a User
Move logic to create a new user to separate class
Display the champion's name

The name used to be a column in the Users table, but now the
champion is a separate model that belongs to user.
Update app name in flash message
Format the champion name before storing it
Set default values for wins and losses
Set default values for Champion stats
Fix indentation
Add challenge types to challenge.rb