Remove environment overwrite in express-server
Update broccoli-caching-writer.

There was a bug in the `canLink` test functionality in 0.4.0 and 0.4.1
that caused an uncaught exception to be thrown in environments that did
not support linking (VMWare Fusion was the example provided).
Remove extra nesting of `addon/styles` tree.

The prior code was actually looking for `addon/styles/styles/` which was
incorrect.
Merge pull request #1963 from rwjblue/update-caching-writer

Update broccoli-caching-writer.
Merge pull request #1964 from rwjblue/fix-nesting-of-addon-styles

Remove extra nesting of `addon/styles` tree.
Use git-repo-info package for repo information.

Extracted this logic into a helper package to make it easier to consume
across our projects.

Details here: https://github.com/rwjblue/git-repo-info
Merge pull request #1971 from rwjblue/use-git-repo-info

Use git-repo-info package for repo information.
Introducing `config` hook for addons

Implements: #1907

A new `config` hook is available for addons. It can be used to alternate application configuration (example: toggling FEATURE flags for Ember) or to read the current config and change addon behaviour (example: importing dependencies conditionally).

Interface:
```
// environment - 'development', 'test', 'production'
// currentConfig - hash with config for given environment
config: function(environment, currentConfig) {}
```
Merge pull request #1959 from gregates/undefined-environment

Remove environment overwrite in express-server
Refactor addon config generation to Project.prototype.config.
Merge pull request #1972 from rwjblue/addon-config

Addon configuration.
Add default `Addon.prototype.config`.
Remove unused root level fixtures folder.
Merge pull request #1978 from rwjblue/remove-extraneous-fixture-file

Remove unused root level fixtures folder.
Merge pull request #1977 from rwjblue/add-default-config-implementation

Add default `Addon.prototype.config`.
Ensure we do not add `ember-addon` twice.
Merge pull request #1982 from rwjblue/do-not-add-ember-addon-twice

Ensure we do not add `ember-addon` twice.
Order dependencies alphabetically
Merge compiled addon/templates into addon/ JS tree.

This allows addon/templates to be properly available inside the
my-addon-name.js file with the correct module name.
Add addon template precomilation smoke test.