Simple ember-cli support.

It is very simple ember-cli support that uses addon mechanism. 

When used in ember-cli project it:
* provide a generator to install cldr and ember-i18n as bower components
* imports cldr and ember-cli to application build
* setup configuration

To use it in ember-cli project:
```
npm install ember-i18n --save-dev
ember generate ember-i18n
```

Implements issue: https://github.com/jamesarosen/ember-i18n/issues/129
@jamesarosen @givanse please note that while we have addon code in ember-i18n repository, the ember-cli will use to separate copies of ember-i18n, potentially in different version.

To use ember-i18n in the application, it must be listed in **bower.json** as dependecy.
Next an addon code need to include this bower dependency to ember-cli build. To make it happen addon must be listed as dev-dependecy in **package.json** (ember-cli automatically scans all node packages for addon code).

It may happen that you will have a different version of ember-i18n in your node_modules directory then in bower_components directory. Apparantly it is the way those things are working if the addon code shares the same repository as library. We can ofcouse separate those competences, but it does not make much sense for me as ember-i18n cannot be used outside of ember.