Adds option to force SSLv3 usage for Subsonic, as mentioned in
enhancement 1930.
Added more verbosity to GUI error message for common network issues when
connecting to a Subsonic server.
Added --restart-or-previous option.

Fixes bug #3524.
Cleaned up NetworkAccessManager behavior from previous commit for
Subsonic, to facilitate SSLv3 usage.
Merge error message & SSLv3 option for subsonic.
Used kNsecPerSec for milliseconds in a second.
Merge --restart-or-previous flag branch.