Google+/Facebook: Merged settings, added icons for the settings of the other connectors

- The settings of "gpluspost" and "fromgplus" as well as the settings of "fbpost" and "fbsync" are merged in one entry. Having it all separated, confused the users.
- If the commercial plugin postToGooglePlus.php from NextScripts is bought and saved into the gpluspost-folder, this is used for postings to Google+
- Icons are now used for the settings. This has a much more appealing look.