Update package.json for ember-cli

* Add `ember-addon` to keywords.
* Add `ember-addon` key with `main` property.
* Rename from `ember-ui-calendar` to `un-calendar` to match bower.json.
Reorganize for ember-cli compatibility

Update `Brocfile.js` to accomodate changed locations of components and
templates.

Update out-of-date devDependencies to get `npm install` and `broccoli
build` to run.
Update README to detail usage as ember-cli addon
Merge pull request #5 from ecbypi/ember-cli-compatibility

[In Progress] Ember CLI compatibility