Multilang

Because there was some interest for localisation (and I rebased my commits) I am re-pullrequesting my final changes. So here is the finished Multilang-Improvement:

Language is now autodetected (was already implemented in F3)
Simply leave the language setting in `config.ini` empty or zero and selfoss will take your browser-setting and will fall back to english if not found.

Furthermore fixes "1 minutes/hours" to singular and changes the date to the country-specific format. (again already there in F3)

Thanks again to ianbogda for the direction in F3