Add internal documentation building via YUIDoc

Run `npm run docs`

Taken directly from Ember.js with minor changes, with exception that
generator will also create HTML docs as well as JSON data. We can fall
back on this until the ember-cli.com site includes this API
documentation.
Add doc signatures for EmberApp

Extremely minimal doc comment blocks. Not yet qualified to complete.
Add documentation about documentation
[Bugfix] update CSP addon, it works now.
Merge pull request #2136 from stefanpenner/update-csp

[Bugfix] update CSP addon, it works now.
Update broccoli related dependencies.

Does not bring any symlinking, but does improve support in preparation.
Merge pull request #2138 from rwjblue/update-deps

Update broccoli related dependencies.
Bump RSVP version
Update CSP addon.

* Fix quoting issue with `self` and `none` default values (they must be
  quoted but they were not previously).
* Enable `unsafe-eval` when running in development environment. Required
  for use with `wrapInEval` (which defaults to "on" when running in
  development mode).
Merge pull request #2140 from thejchap/recursive-process-fix

Bump RSVP version
Merge pull request #2141 from rwjblue/update-csp-addon

Update CSP addon.
Use injection as example in initializer blueprint

Fixes #2147
Merge pull request #2148 from jgwhite/fix-2147

Use injection as example in initializer blueprint
Implement {{content-for 'head'}}.
Merge pull request #2153 from rwjblue/implement-content-for

Implement {{content-for 'head'}}.
Update broccoli-asset-rev.
Merge pull request #2167 from abuiles/update-broccoli-assets-rev

Update broccoli-asset-rev.
Update CHANGELOG.md.

Prepare for 0.0.47.
Use symlinking.
Bump version.