add User Mongoose model
store entry in db when user links account
expose user account data with new format
update player like system to use new user object format
store soundcloud data in db when user links account
update frontend to use new soundcloud credentials object
remove development log messages
add unlink soundcloud account functionality
add ability to unlink youtube account
Merge pull request #47 from Fauntleroy/users-stored-in-db

Users stored in db
fixes #46