Fix sign up not setting user on session

No issue found

- Grab user out of api response from users[0]
Merge pull request #2766 from jgable/fixRegister

Fix sign up not setting user on session
Refactor API arguments

closes #2610, refs #2697

- cleanup API index.js, and add docs
- all API methods take consistent arguments: object & options
- browse, read, destroy take options, edit and add take object and options
- the context is passed as part of options, meaning no more .call
  everywhere
- destroy expects an object, rather than an id all the way down to the model layer
- route params such as :id, :slug, and :key are passed as an option & used
  to perform reads, updates and deletes where possible - settings / themes
  may need work here still
- HTTP posts api can find a post by slug
- Add API utils for checkData
Merge pull request #2732 from ErisDS/issue-2610

Cleanup & Refactor API option names
Improve signin

Ref #2413

- Remove fixture and use actual API
- Store and send down actual logged in user data
- Refactor isLoggedIn to use computed property on application
- After signin, update user data in dependency container
- Add CSRF to all routes and controllers via initializer
- Update authenticated route to check for user.isLoggedIn
- Add notifications for signin error
- Add notifications.showAPIError helper
- Add plumbing for refreshless signup to doSignUp in admin controller