Add function to open connections in gatttool
Add function to open connections in gatttool

The do_connect() function was created to open unix/l2cap sockets. It is
used by primary, characteristics and characteristics value options.

pkarasev3/bluez,silent-snowman/bluez,ComputeCycles/bluez,mapfau/bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,pkarasev3/bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,silent-snowman/bluez,mapfau/bluez,silent-snowman/bluez,pkarasev3/bluez,mapfau/bluez,silent-snowman/bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,pkarasev3/bluez