[PATCHes] Add BaudRate options for GPS providers

[Bastien Nocera]

Heya,

First patch changes the SetOptions API to pass a{sv} instead of a{ss}
and modifies the GConf to actually use those integers.

The second patch fixes an object leak (we were leaking the GypsyDevice
object if we changed between devices whilst running), and adds support
for the BaudRate options.

Tested locally with gypsy master, and my crummy ND-100 USB GPS.

Cheers