Lots of big changes, please test and report any problems :)
- option to stop sync on mobile data and/or battery
- service automatically starts on boot
- exit button removed (not useful any more with the changes above)
- "create" button in "add repo/node" screens also shows in the ActionBar on Gingerbread now
- use ActionBar icon to delete repo/node instead of preference item
- fixed logging for syncthing binary
- major refactoring and code style change