add helper method to create Song and Sound from SoundCloud url
simplify API request code by using SoundCloud API, address john's comments
add uniqueness check to Sound by sound_type and location
* also add test for trying to resolve the same SoundCloud sound twice
[jo] add use show page, user links, group links
[jo] clean up routes
[jo] allow groups to be added/destroyed; needs permissions audit, application js/css not loading
address john's comments
* add begin/rescue
* new+save -> create
Merge pull request #19 from byronmwong/soundcloud_helper

add helper method to create Song and Sound from SoundCloud url
[jo] rename instance var used for group creation
Merge pull request #20 from johnmanong/feature/add-remove-groups

Feature/add remove groups