Remove calls to git from gemspec for Windows compatibility
user
```ruby
# -*- encoding: utf-8 -*-
require File.expand_path('../lib/rails_admin/version', __FILE__)

Gem::Specification.new do |s|
  s.add_development_dependency('devise', '~> 1.1')
  s.add_development_dependency('dummy_data', '~> 0.9')
  s.add_development_dependency('rspec-rails', '~> 2.3')
  s.add_development_dependency('simplecov', '~> 0.3')
  s.add_development_dependency('ZenTest', '~> 4.4')
  s.add_runtime_dependency('builder', '~> 2.1.0')
  s.add_runtime_dependency('rails', '~> 3.0.3')
  s.authors = ["Erik Michaels-Ober", "Bogdan Gaza"]
  s.description = %q{RailsAdmin is a Rails engine that provides an easy-to-use interface for managing your data}
  s.email = ['sferik@gmail.com']
  s.extra_rdoc_files = ['LICENSE.mkd', 'README.mkd']
  s.files = Dir['Gemfile', 'LICENSE.mkd', 'README.mkd', 'Rakefile', 'app/**/*', 'config/**/*', 'lib/**/*', 'public/**/*']
  s.homepage = 'http://rubygems.org/gems/rails_admin'
  s.name = 'rails_admin'
  s.platform = Gem::Platform::RUBY
  s.rdoc_options = ['--charset=UTF-8']
  s.require_paths = ['lib']
  s.required_rubygems_version = Gem::Requirement.new('>= 1.3.6') if s.respond_to? :required_rubygems_version=
  s.rubyforge_project = 'rails_admin'
  s.summary = %q{Admin for Rails}
  s.test_files = Dir['spec/**/*']
  s.version = RailsAdmin::VERSION
end
```
assistant