Merge pull request #69 from ospreys-2014/user_branch

User branch
partly implemented ajax for ratings. commented out to resume development later
add jquery library
correct the user_id in the hidden input so that user will be recorded while rating an artist
enclose in span tags to accommodate future jquery to update the rating number upon ajax callback
Merge pull request #71 from ospreys-2014/model_migration

Model migration
add paperclip gem to gemfile
add validation for avatar
fix migration for avatar
add default pic to artists when they dont upload their own
Merge branch 'user_branch' of https://github.com/ospreys-2014/Kendrick into user_branch