[connectionagent] supress autoconnecting when tethering is enabled.

connman will bring cell online when wifi tethering is enabled.
[connectionagent] initialize tetheringEnabled correctly.

Also remove Q_FUNC_INFO.
don't use wifi tech is NULL
fix use
Merge pull request #14 from lpotter/tethering

[connectionagent] supress autoconnecting when tethering is enabled.