Added better support for CanCan#accessible_by

Added an `action` optional argument to AuthorizationAdapter#scope_collection.
The controller passes in the action that is currently being performed so
that authorization adapters can correctly scope collections based on
different controller actions.

Also implemented it on the `CanCanAdapter` so that we offer full support
of the accessible_by functionality.
Only call AuthorizationAdapter#scope_collection for collection.

This commit ensures that #scope_collection is only used to retrieve the
collection, not when finding a single resource. The issue was that
resources may be scoped out which result in an
ActiveRecord::RecordNotFound when it should result in a authorization
exception.
Merge pull request #2131 from gregbell/cancan-better-accessible_by-support

Added better support for CanCan#accessible_by
fix breadcrumb bug so non-belongs_to resources get `display_name` called

before this fix, non-nested (non-belongs_to) resources in the URL wouldn't
get massaged by `display_name` so only an ID would be shown.
make ResourceCollection behave more like a Hash

unneeded complexity is unneeded
Merge pull request #2078 from Daxter/refactor/resource_collection

Refactor ResourceCollection
improve belongs_to error message

now it won't throw a huge, useless error message

closes #1367
[Added] option to hide new record link for has_many form and changed documentation.
Merge pull request #2134 from developer88/master

Hide new record link for has_many form
prevent assets from being registered multiple times

JavaScript and CSS registrations are now stored inside a Set and a
Hash, respectively, to ensure that no duplicates are created.
Merge pull request #2139 from Daxter/bugfix/1845-asset-registration

[1845] prevent assets from being registered multiple times
refactor menu item attributes

This commit merges `menu_item_menu_name` into `navigation_menu_name`, as
they both appear to have the same purpose. By doing so, this seems to fix a
previously unreported issue of belongs_to nested resources. Now, the menu
items for those nested resources show up in a unique navigation menu
specific to the parent resource.
Merge pull request #1987 from Daxter/refactor/1967-menu-updates

Refactor [1967] Menu Updates
Index results label fix
Merge pull request #2135 from mindhalt/index-results-label-fix

Fix translations for languages with multiple plural forms
improve the document
move things around

+ moved the spec into the view_helpers folder
+ moved the `display_name` method to the top of the file
exclude association methods from `display_name` helper
Merge pull request #2119 from guangnan/master

Fix inconsistent vocabulary in the docs
Merge pull request #2147 from Daxter/bugfix/2052-exclude-associations-from-display-name-methods

[2052] Exclude associations from display name helper
Closes #2052