Fixes #5221: Adds a helper method to allow a model instance to inquire if the instance is authorized for a particular permission.

Model instances can be asked directly if they are authorized for a particular
permission by, for example, calling 'instance.authorized?(:view_model)'. This
abstracts and centralizes some of the repetitiveness of having to instantiate
an authorizer and pass the instance to the 'can?' method as the object of inquiry.
Fixes #5664 - Host filters can use taxonomies

Also disables taxonomy filters on resources that do not support them.
fixes #5690 - determine host taxonomy fact based on setting value
Fixes #5689 - Plugin permissions are migrated too
fixes #5726 - parameter values missing from host#show API call
fixes #5788 - before_destroy missing from EnsureNotUsedBy.new in SmartProxy model
fixes #5671 - LookupValue name should be matcher, value is too long
fixes #5631 - API v2 - host and hostgroups show.json.rabl should show all puppetclasses in child node
Fixes #5645: Fixes session undefined error when user has a default taxonomy set.
fixes #5685 - add :path_ids to with_taxonomy_scope instead of subtree_ids for SmartProxy select dropdowns
fixes #5836 - Welcome page - missing rel attribute
Fixes #5946 - Only call fact_name_class.maximum if necessary.
Fixes #5696 - Allow taxonomy and roles display
fixes #5966 - pin execjs for Ruby 1.8 compatibility
fixes #5793 - add pkg:generate_source rake task to create tar.bz2
fixes #5987 - remove unused packaging files
fixes #5965: removed 8443 port from the suggested ovirt url
fixes #5869 - permit accents in user names on Ruby 1.8
fixes #5963 - fix Role has_permission? function
fixes #6030 - update list of VMware guest types