ApplicationSession: fix initialization
ApplicationSession: fix initialization

When the user sets the DefaultConfig to StandAlone and a QI_URL variable is
there, the ApplicationSession constructor would throw

Change-Id: I474fa96099d731a574ac61b7955a46c3808f6104
Reviewed-on: http://gerrit.aldebaran.lan/64103
Reviewed-by: hcuche <2a0975cc082cedff4d4350e3f6ec187146151bc6@aldebaran.com>
Reviewed-by: vpaleologue <cb19838a79eb484e12a6960acfbf7c16dfdb80d9@aldebaran-robotics.com>
Tested-by: pdaouadi <fc1eb3334d3fdad315bae23aa166bc70bd434067@aldebaran-robotics.com>

aldebaran/libqi,aldebaran/libqi,aldebaran/libqi