feat(user): add UserDataService for seeding and searching user

* add UserDataService and specs
* implement update method on controller, ensuring either admin or
  the user herself
* clean up user model
* export User model as module instead of, as in others, the as
  attribute on exported module
* add sample user data json file
* add user seeding to UserDataService
chore(stylesheets): move sass/_nav.scss to nav component dir in core

* rename to nav.scss
chore(specs): modularize specs, moving all into respective component dirs
refactor(test/.jshintrc): allow camelcase because google uses it for provider fields