Add expected devstack functions

Devstack expects that there are certain plugin function names which we
have not defined. This defines these function names. They are just
empty functions to aviod command not found errors and provide no
additional functionality.

Change-Id: I281abee72370a583282f3d9ad7c3b572496d025a

devstack/plugin.sh

@@ -80,6 +80,34 @@ function cleanup_networking_powervm {
     :
 }
 
+# Devstack Required Functions
+# - These are required for devstack to stack properly
+# - They are intentionally left blank here
+
+function neutron_plugin_configure_dhcp_agent {
+    :
+}
+
+function neutron_plugin_install_agent_packages {
+    :
+}
+
+function neutron_plugin_configure_plugin_agent {
+    :
+}
+
+function neutron_plugin_setup_interface_driver {
+    :
+}
+
+function neutron_plugin_configure_l3_agent {
+    :
+}
+
+function neutron_plugin_create_nova_conf {
+    :
+}
+
 # Core Dispatch
 # -------------
 if [[ "$1" == "stack" && "$2" == "pre-install" ]]; then