Update partials module to fix locals bug

res.locals was not accessible in partials in previous version. Fallback
to app.locals had one major drawback: custom css were added but never
removed. So browsing the application would add always the same css, more
and more.

This was a severe memory leak.

Closes #180
Merge pull request #193 from fzaninotto/fix_partial_locals

Update partials module to fix locals bug