Please describe the problem:
File roller uses ~/.fr-* directories to store temporary files to be previewed.

On systems with little space in $HOME (like public shells or university accounts), these temporary files can make the user exceed its disk quota with a simple preview.

To solve this, File roller should follow the XDG Base Directory specification and store its temporary files in $XDG_CACHE_HOME.

XDG Base Directory specification: http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html

Steps to reproduce:
0. Set XDG_CACHE_HOME to /tmp
1. Set user quota to 10 MB on ~ and unlimited on /tmp
2. Open an archive with big (> 10MB) PDFs stored in /tmp and open one (double-click) one the contained PDF


Actual results:
Disk quota exceeded, PDF cannot be opened. 

Expected results:
The PDF document should be opened without problems. No disk space should be used in $HOME.

Does this happen every time?
Yes

Other information: