Add missing end to generic bucket and remove capability method [GH-94]

lib/vagrant-cachier/bucket/generic.rb

@@ -2,10 +2,6 @@ module VagrantPlugins
   module Cachier
     class Bucket
       class Generic < Bucket
-        def self.capability
-          :generic_cache_dir
-        end
-
         def install
           if @configs.has_key?(:cache_dir)
             @name = @configs.has_key?(:name) ? "generic-#{@configs[:name]}" : "generic"
@@ -17,3 +13,4 @@ module VagrantPlugins
       end
     end
   end
+end