Set autoconnect property for a service after successful connection

:Release Notes:
If the autoconnect property is tried to be set to true earlier connman
doesn't accept the change, so change it only after the connection is
successful.

:Detailed Notes:

:Testing Performed:
Verified that the autoconnect value is true using "connmanctl" for a connected
service.

:Issues Addressed:
[GF-37438] Settings: Wireless Connection: After reboot, TV is not connecting
           automatically to wireless network.

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <simon.busch@lge.com>

Change-Id: Ia6c7854c5211d336184e13425a7c2df57a1061d1
Reviewed-on: https://g2g.palm.com/3679
Reviewed-by: Build Verification
Reviewed-by: Sapna Todwal <sapna.todwal@lge.com>
Tested-by: Sapna Todwal <sapna.todwal@lge.com>