Fix the link for the PyLucene installation docs in General Settings.

General Settings was pointing to an old, broken link for PyLucene
installation docs. This is now updated to point to the current location.
Fix Apache configuration files to explicitly use +FollowSymLinks.

The Apache configuration files we generate add a
"-Indexes FollowSymLinks," but apparently this isn't sufficient on some
installs. The "+" should be added before "FollowSymLinks". This is a
simple change to explicitly add this.
Fix a small vulnerability in the file change list in the diff viewer.

A change from a while back for some reason accidentally introduced
making entries in the file change list "safe", meaning that any HTML in
the filename would be rendered in the page instead of escaped. This was
due to these using the escapejs filter.

I can't see any reason why we'd want to use this filter in this case, so
I'm removing it, fixing the vulnerability.