Clean up notification settings in glance-api.conf

Currently, rabbitmq settings in glance-api.conf are hard-coded and
overrides to rabbitmq settings in environment will not be reflected in
configuration file.  This change addresses that while also only writing
rabbitmq/qpid settings when an appropriate notification strategy is
selected.

Change-Id: I9d06d4b1e030f14293d143021bd78d732adafcc2
Closes-Bug: #1273020
Add attribute and configuration for show_image_direct_url

- Add default["openstack"]["image"]["api"]["show_image_direct_url"]
  which defaults to "False"
- Add option into glance-api.conf.erb
- Added test for show_image_direct_url setting
- Adjusted README to reference attribute

Change-Id: I83cd13db1d102118d696d371d94197044abf8e94
Closes-Bug: #1274960
Upgrade/Update rubocop

Now that almost all of the rubocop blueprints have been completed, make
one final pass through all of the cookbooks ensuring they're all in
sync with each other.

- Upgrade rubocop to 0.18.1
- Fix violations caused by 0.18.1 upgrade
- Move Excludes for non-existent folders to Includes so they
  automatically cover future additions

Change-Id: If2931d371911c10787bbb2c2bf1c51881e3c4488
Implements: blueprint lint-and-unit-testing-for-havana
Merge "Clean up notification settings in glance-api.conf"
Merge "Upgrade/Update rubocop"