remove useless export of the workspace controller
ignore .log files
ignore files related to bower tasks
introduce URLRewriter

In order to better handle URLs in Dahu this commit introduces URLRewriter.
From its name, the URLRewriter allows for URL Rewriting.

A simple example would be to rewrite the following URL:

    dahufile:@screencast/img/somePicture.png

To

    dahufile:/home/barraq/screencast/hello/img/somePicture.png

Basically replacing `@screencast` by the path of the screencast project.