TEST-16 Create global variable for default key

Alternate key may be provided by setting varialble
GLOBAL_VM_PRIVATE_KEY=<path to key> and
updating the pub_key in the _preload_parameters.py

Change-Id: I3abcaf8a38aa0bc5fdc0c2b2ac0796b9f5820f46
Signed-off-by: Jerry Flood <jf9860@att.com>
diff --git a/robot/resources/global_properties.robot b/robot/resources/global_properties.robot
index 442a69c..871f992 100644
--- a/robot/resources/global_properties.robot
+++ b/robot/resources/global_properties.robot
@@ -24,3 +24,4 @@
 ${GLOBAL_VID_UI_TIMEOUT_SHORT}    20s
 ${GLOBAL_VID_UI_TIMEOUT_MEDIUM}    60s
 ${GLOBAL_VID_UI_TIMEOUT_LONG}    120s
+${GLOBAL_VM_PRIVATE_KEY}   ${EXECDIR}/robot/assets/keys/robot_ssh_private_key.pvt
\ No newline at end of file