Update webui.py
removed absolute path from download / preview

I run recoll-webui under a differnt path using WSGI and mod_proxy. So the application runs under /recoll/

The download link should therefore point to
/recoll/download (not) /download

This change fixes that
removed link to file, download is default

download links to files directly (file://) are not supported anymore by most browsers. Basides, I have the application running anyhow on a different server. Network file path' on local machines are anyhow different.
WSGI / Apache2 setup described
Formating improved
Merge pull request #27 from jobe451/master

Headless setup under apache2 / ubuntu 12.04