update Access-Control-Allow-Origin header for staging
add endpoint for checking availability of mods to be categorized by the current_user
Merge branch 'master' of github.com:LiminalSoftware/SR-Rails-API
fix bug in mods#available
Merge branch 'master' of github.com:LiminalSoftware/SR-Rails-API
fix mods#available (again) to respond to jsonp
Merge branch 'master' of github.com:LiminalSoftware/SR-Rails-API