Enforce function declaration format in bash8

Check that function calls look like ^function foo {$ in bash8, and fix
all existing failures of that check.  Add a note to HACKING.rst

Change-Id: Ic19eecb39e0b20273d1bcd551a42fe400d54e938
diff --git a/lib/neutron_thirdparty/bigswitch_floodlight b/lib/neutron_thirdparty/bigswitch_floodlight
index 24c1044..f03de56 100644
--- a/lib/neutron_thirdparty/bigswitch_floodlight
+++ b/lib/neutron_thirdparty/bigswitch_floodlight
@@ -8,11 +8,11 @@
 BS_FL_CONTROLLERS_PORT=${BS_FL_CONTROLLERS_PORT:-localhost:80}
 BS_FL_OF_PORT=${BS_FL_OF_PORT:-6633}
 
-function configure_bigswitch_floodlight() {
+function configure_bigswitch_floodlight {
     :
 }
 
-function init_bigswitch_floodlight() {
+function init_bigswitch_floodlight {
     install_neutron_agent_packages
 
     echo -n "Installing OVS managed by the openflow controllers:"
@@ -32,19 +32,19 @@
     sudo ovs-vsctl --no-wait set-controller ${OVS_BRIDGE} ${ctrls}
 }
 
-function install_bigswitch_floodlight() {
+function install_bigswitch_floodlight {
     :
 }
 
-function start_bigswitch_floodlight() {
+function start_bigswitch_floodlight {
     :
 }
 
-function stop_bigswitch_floodlight() {
+function stop_bigswitch_floodlight {
     :
 }
 
-function check_bigswitch_floodlight() {
+function check_bigswitch_floodlight {
     :
 }