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