Remove the scriptz submodule and hard-commit the files.

The submodule is a leftover from when this project was intended to work
as a series of microservices. It was meant to provide common
functionality to the builds for every microservice. That's no longer the
case, and the submodule is a pain-point both in on-boarding new
developers and running the Docker build.

script/include/dev_server_functions.inc.sh

@@ -0,0 +1,8 @@
+# dev_server_functions.inc.sh: Functions used by the dev_server script
+
+# Used to ensure a SIGTERM is sent to all process in the current process group
+reap() {
+   kill -s SIGTERM -- "-$$"
+   sleep 0.1
+   exit
+}