core extensions

Sprockets::StaticCompiler: option ":zip_files"

After vendor/plugins were removed from rails, the new method to create
plugins is to create gem plugins. Most of the time if you create a
new plugin in rails application's directory, you want to extract
something from that application and use it immediately, ie. add
such line to Gemfile:

  gem 'foo', :path => './vendor/foo'

This commit makes plugin new generator to add such line automatically.

ruby 1.9 related refactoring

get rid of using instance_variable_names method from AS

- instance_variables return symbols in 1.9
- there is instance_variable_defined? method

use stub instead of redefining method to suppress warnings

if turn available then MiniTest::Unit.respond_to?(:use_natural_language_...

Fixed after_initialize callbacks call on AR model #dup

add benchmark helper that works in erb

Remove more references to Test::Unit

all tests pass, not the number of tests.

Array.wrap is an overhead as there is already check for class

revert "fixing some tests on ruby 1.9.3"