New stop plug-in

A means of controlling when OBMC Boot Test stops.

Also, added additional plug-in support.

Change-Id: I77051805451ecf4431b79b54b090860ac858ec0b
Signed-off-by: Michael Walsh <micwalsh@us.ibm.com>
diff --git a/bin/plug_ins/Stop/supports_obmc b/bin/plug_ins/Stop/supports_obmc
new file mode 100644
index 0000000..d965c8a
--- /dev/null
+++ b/bin/plug_ins/Stop/supports_obmc
@@ -0,0 +1 @@
+# The presence of this file tells obmc_boot_test that this plug-in supports Open BMC.