upgrade mocha 0.14 and remove deprecation warning

<pre>
Mocha deprecation warning: Change `require 'mocha'` to `require 'mocha/setup'`.
</pre>

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11896 e93f8b46-1217-0410-a6f0-8f06a7374b81

Gemfile

@@ -78,7 +78,7 @@ end
 
 group :test do
   gem "shoulda", "~> 3.3.2"
-  gem "mocha", "~> 0.13.3"
+  gem "mocha", ">= 0.14", :require => 'mocha/api'
   if RUBY_VERSION >= '1.9.3'
     gem "capybara", "~> 2.1.0"
     gem "selenium-webdriver"