Fixed issues with RSS feed links
added cache to get default country and currency
added strict test ===
fixed painful issues on tests that generated random errors on positions
addded test data for position tests
Merge pull request #507 from bibich/improvements

Improvements :
- added cache on default country / currency
- fixed issues on RSS links in default front office template
- fixed random issues on position tests
Merge branch 'master' of https://github.com/thelia/thelia into export