run_test_suite.sh: Renamed to run_test_suite

Because it's an executable that should be interchangeable with another
kind of script (e.g. Python).
vagrant*: Run test suite in virtual machines

The new `vagrant_tests_runner` is a wrapper around Vagrant and
`run_test_suite`. The point of adding this is that we'll be able to:
1) Run the test suite on different virtual systems.
2) Test that the deployment of the application as a whole works
  2.1) Test that the app is correctly deployed as a Python library
vagrant: Add a systemupdate as a first step

Otherwise, the installation of some packages in Ubuntu fails due to errors
"Failed to Fetch [source]".
extra/check_code.sh: Include working `netcontrol` directory in $PYTHONPATH

Otherwise, Pylint fails to resolve imports within the project.
Merge branch 'vagrant-vms'