Require jQuery from the default bootstrap template.

This is still completely customizable, but I believe that 90% of the
time this is the correct choice. `jquery-rails` is one of the
default gems for a new Rails install.
Require `Sprockets` from Ember::Rails::Engine.

Resolves https://github.com/emberjs/ember-rails/issues/170.
Allow `application.js` injection in more cases.

Previously, when the `ember:bootstrap` generator was run it would only
inject the template if `require_tree` was found within the existing
file. This meant that if the file was empty (ala `rails-api`) or simply
didn't call `require_tree` the generator was silently failing.
Merge pull request #293 from rjackson/require_sprockets_from_engine

Require `Sprockets` from Ember::Rails::Engine.
Merge pull request #292 from rjackson/require_jquery_in_the_application_template

Require jQuery from the default bootstrap template.
Merge pull request #294 from rjackson/handle_more_cases_for_application_injection

Allow `application.js` injection in more cases.
Added support for downloading a tagged version of ember or ember-data

- fixed a typo in the help test
- Now rightfully downloading the min file for production instead of the debug version
Merge pull request #295 from hajee/tagged_release

Added support for downloading a tagged version of ember or ember-data