[Command::Project] Include options in subcommands.

lib/cocoapods/command/project.rb

 module Pod
   class Command
     module Project
-      def self.options
+      module Options
+        def options
           [
             ["--no-clean",     "Leave SCM dirs like `.git' and `.svn' intact after downloading"],
             ["--no-doc",       "Skip documentation generation with appledoc"],
@@ -9,6 +10,11 @@ module Pod
             ["--no-update",    "Skip running `pod repo update` before install"],
           ].concat(super)
         end
+      end
+
+      def self.included(base)
+        base.extend Options
+      end
 
       def initialize(argv)
         config.clean             = argv.flag?('clean', true)