as is_heat_enabled

this is missing, and the code assumes "heat" to be in the
enabled services list otherwise.

Change-Id: Ib0a7db04d8e38b58aca48261308e7c4d1fd43972
diff --git a/lib/heat b/lib/heat
index 2d9d863..902333e 100644
--- a/lib/heat
+++ b/lib/heat
@@ -45,6 +45,13 @@
 # Functions
 # ---------
 
+# Test if any Heat services are enabled
+# is_heat_enabled
+function is_heat_enabled {
+    [[ ,${ENABLED_SERVICES} =~ ,"h-" ]] && return 0
+    return 1
+}
+
 # cleanup_heat() - Remove residual data files, anything left over from previous
 # runs that a clean run would need to clean up
 function cleanup_heat {