[libvirt] [PATCH 4/5]: Move the sendtarget command into the login command

A small bugfix; we only need to call the iscsiadm sendtarget command when we are first logging in; we don't need to do it for logout. Move the sendtarget command into the Login() function. Changes since last time: 1) Make const char *cmdsendtarget into const char *const cmdsendtarget based on feedback from Jim. Signed-off-by: Chris Lalancette <clalance@redhat.com>