Topbar5

Plugin interface for registering a plugin
including
name, url, description, author, author url,
adding permission
adding roles
manipulating menu items.

example plugin can look like this one:
```ruby
Foreman::Plugin.register :discovery do
        name 'Discovery plugin'
        author 'Greg Sutcliffe'
        description 'MaaS Discovery Plugin engine for Foreman'
        version VERSION
        requires_foreman '1.3'

        # Add permissions
        security_block :discovery do
          permission :perform_discovery, {:discovers => 
                                [:index, :show, :update, :new, :edit, :destroy, 
                                 :create, :auto_complete_search,
                                 :update_multiple_organization,
                                 :select_multiple_location,
                                 :refresh_facts,
                                 :update_multiple_location,
                                 :submit_multiple_destroy, 
                                 :multiple_destroy]}
        end

        # Add a new role called 'Discovery' if it doesn't exist
        role "Discovery", [:perform_discovery]

        #add menu entry
        menu :top_menu, :discovery, :url_hash => {:controller=> :discovers, :action=>:index},
                                    :caption=> 'Discovered Hosts',
                                    :parent => :hosts_menu,
                                    :after=>:hosts
      end
```