Tests use their own settings

This way example and tests are independents.

I also used memory for the sqlite3 database and added two directories to
the `.gitignore` file: `.settings`(added automatically by by eclipse) and `whoosh_index`(I don't think it's necessary to distribute spirit?)
It seems that whoosh index is changed during tests. And changes made in python3 are not compatible in python2: a pickle error occurs.