Added total_stat_between and between class methods
Refactored activity totaling using the new activity class method
Started implementing the refactor for the highest kilometer method
Finished refactoring of highest methods
Changed activities_for method to be a class method on activity
Changed @user.activities_for to use challenge.period
Changed @challenge to use @challenge.period in user methods
Added list class method for getting a list of activities for users
Changed test to use challenge.period for activity list
Changed sum_stat to use a date range
Removed redundant methods
Fixed some style things
Refactored challenge methods to use refactored user class methods
Fixed a bunch of test
Added ? methods for distance, ascent and achievements
Merge pull request #28 from justinhennessy/jh_refactor_highest_kilometers

Jh refactor highest kilometers