promotion - remove legacy promotion in the UI

This commit contains changes to remove the legacy
promotion of products/repos/packages/errata/distributions
from the UI (only).  After this change, the only content type
that may be promoted is content views.

Note: This is an ammended commit.  Previously it had also removed
actions from the errata and packages controller that were no longer
used, as well as the view partials on those controllers.  Based on
pull request feedback, we will leave those in place to be reused/
modified when logic is added to content search.  At that time,
we can remove those files, if no longer needed.  Files involved
included:
   app/controllers/errata_controller.rb
   app/controllers/packages_controller.rb
   app/views/errata/_packages.html.haml
   app/views/errata/_show.html.haml
   app/views/packages/_changelog.html.haml
   app/views/packages/_dependencies.html.haml
   app/views/packages/_filelist.html.haml
   app/views/packages/_show.html.haml
Merge pull request #2137 from bbuckingham/delete-legacy-promotion

promotion - remove legacy promotion in the UI
Merge remote-tracking branch 'upstream/master' into delete-legacy-promotion
Merge pull request #2166 from daviddavis/delete-legacy-promotion

Merging master in delete-legacy-promotion
Removing legacy path from api
delete-legacy-promotion - ui/model - make view required for system and akey

This commit contains changes so that content view is required
for systems and activation keys.  Previously, the user could
assign systems/keys an environment, but omit the view.
Merge pull request #2218 from daviddavis/bbuckingham-delete-legacy-promotion

Requiring content views for systems and activation keys
Merge remote-tracking branch 'upstream/master' into delete-legacy-promotion
Merge pull request #2221 from daviddavis/temp_1368040499

Merging in master
Merge pull request #2167 from daviddavis/rm_legacy_path_api

Removing legacy path from api
API - Requiring content view for activation keys
Merge remote branch 'upstream/master' into delete-legacy-promotion-merge

Conflicts:
	app/assets/javascripts/promotions/promotion.js
	app/assets/javascripts/systems/system_edit.js
	app/models/system.rb
	app/views/systems/_edit.html.haml
	spec/models/system_spec.rb
Merge pull request #2309 from daviddavis/merge-delete-legacy-promotion

Merging master into delete-legacy-promotion
Content views: list and show default content views

List and show default content views in the API.
Merge pull request #2315 from daviddavis/temp_1368724127

Content views: list and show default content views
Merge pull request #2277 from daviddavis/temp_1368547562

API - requiring content view for activation keys
content views - update authorization to handle headpin mode

This change is to ensure an authorization failure does not
occur during headpin mode.
content views - include all views in select on systems, akeys...

This commit is to remove the usage of 'non_default' scope
when retrieving a list of content views.  This means
that the list returned will all in the environment.
This can be useful on the 'select' input that is used
on Systems and Activation Keys.
content views - enable/disable buttons on env content view selector

This commit contains changes to enable/disable the save/cancel
buttons associated with the 'environment / content view' selector.

E.g.
buttons initially disabled
user changes env or view, buttons enabled
user save change, buttons disabled
user cancels change, buttons disabled
path selector - update behavior of select_mode=single

This commit changes the behavior of the 'single' select mode,
where a user can only have 1 environment selected at a time.

Example:
- assume dev, test, prod exist
- dev is selected

Scenario: User wants to select 'test'

Before the change:
- unselect dev and then select test

After the change
- select test (and dev is automatically unselected)

After the change: