Update flask_mako.py

Firstly, lemme say I'm super thankful for this extension, and use it in pretty much *all* of my flask apps.
Secondly, lemme say that everytime I do so, I have to go to line #217 of flask_mako.py and delete `translated` to avoid this traceback:

```
flask_mako.TemplateError
TemplateError

File "/home/decause/.virtualenvs/hackupstate/lib/python2.7/site-packages/Flask_Mako-0.3-py2.7.egg/flask_mako.py", line 217, in _render
raise Translated
```