Add support for the registration view model

[typerandom]

Adds support for the registration view model.

Notes

The reason why I've added default fields is just so that the SDK is backwards-compatible with stormpath-express < v3.0.0. I.e. if the GET request to /register fails, then it simply defaults to the standard default form.

Also, I first named the method getRegisterViewData as getRegisterationViewData. Registration sounds better to me, but decided to renamed it back to Register because it was more consistent with the endpoint.

Any thoughts?

How to verify

1. Checkout this branch.
2. Build it ($ npm run build).
3. Link it ($ npm link).
4. Checkout the framework-spec-upgrade branch of express-stormpath.
5. Link it ($ npm link).
6. Checkout the the React example app.
7. Link to our React SDK feature branch ($ npm link react-stormpath).
8. Link to our Express feature branch ($ npm link express-stormpath).
9. Start the app ($ npm start).
10. Navigate to /register.
11. Verify that the default registration form looks and works as expected.
12. Open up app.js and modify the web.register.fields.
13. Start the app (step 5).
14. Navigate to /register.
15. Verify that the register form looks and works as as configured by web.register.fields.

Fixes #32.

[timothyej]

What has actually changed here, is it another type of whitespace or what? :)

[timothyej]

This works just like expected 👍

Regarding getRegisterViewData I'm fine with that since that's what the view/route is called on the express side.