Remove rescue_from from exception handler

This was discussed on #263, and we decided that is not necessary these rescues, so here I remove them.

With this change, in production we need to show the not found page, that used to be with the Neighbor.ly Header and Footer, but now, we show just a simple page, see below:

![screen shot 2014-05-30 at 10 37 29 am](https://cloud.githubusercontent.com/assets/230476/3131329/4c617d5e-e803-11e3-8de0-1dc5a724f5bf.png)

Following some of the biggest companies, they usually just show this kind of error page, simple and clean.

cc/ @snconnolly any concerns with this change on the not found page?