Allow boot_utils users to pass stack_mode/quiet.

Where at one time users had to do this:

    Set Global Variable  ${stack_mode}  skip
    Set Global Variable  ${quiet}  ${1}
    REST Power On

They may now do this:

    REST Power On  stack_mode=skip  quiet=1

Change-Id: I53d34a591a529d890e85b3f7b23a322d2f26e7e2
Signed-off-by: Michael Walsh <micwalsh@us.ibm.com>
diff --git a/extended/obmc_boot_test_resource.robot b/extended/obmc_boot_test_resource.robot
index 6c64da8..9bfc8b3 100644
--- a/extended/obmc_boot_test_resource.robot
+++ b/extended/obmc_boot_test_resource.robot
@@ -6,6 +6,7 @@
 Library   ../lib/state.py
 
 Library   ../lib/obmc_boot_test.py
+Library   Collections
 
 *** Variables ***
 # Initialize program parameters variables.
@@ -69,12 +70,15 @@
 ###############################################################################
 OBMC Boot Test
     [Teardown]  OBMC Boot Test Teardown
-    [Arguments]  @{arguments}
+    [Arguments]  ${pos_arg1}=${EMPTY}  &{arguments}
 
     # Note: If I knew how to specify a keyword teardown in python, I would
     # rename the "OBMC Boot Test Py" python function to "OBMC Boot Test" and
     # do away with this robot keyword.
 
-    OBMC Boot Test Py  @{arguments}
+    Run Keyword If  '${pos_arg1}' != '${EMPTY}'
+    ...  Set To Dictionary  ${arguments}  loc_boot_stack=${pos_arg1}
+
+    OBMC Boot Test Py  &{arguments}
 
 ###############################################################################