virtual-stb: Add readyness notification
make check: Don't explicitly list python files to test

This increases coverage as you don't have to remember to add your python
file to the list in the Makefile.  It also saves 15 lines of Makefile.
fixup! virtual-stb: Add readyness notification
virtual-stb: Rewrite to not use netstat, use /proc directly

Simpler code and one fewer dependency.
virtual-stb: Pylint fixes