Add O2 Germany MMS settings

http://hilfe.o2online.de/t5/Mobiles-Internet-und-LTE/Verschiedene-Proxy-Einstellungen-bei-o2/td-p/214769

Confirmed by TJC user:

https://together.jolla.com/question/38555/mms-issues-hints-for-debugging-and-helping-us-to-improve/#post-id-38866