Functional tests
This is the integration of heptapod-tests in the HDK.
The new instructions in the README should make it easy to use for anybody.
The added value is that the launcher script already passes the proper option values to test the wished Heptapod development instance: ports, paths and the mere fact that the default values are mean for Docker instances.
It also gives a starting example for people wishing to do something different, e.g., run the functional tests for heptapod-stable
(not directly supported by this MR which is for the heptapod
branch of the HDK, but not that different)
Closes #1 (closed)