Do not run the test suite for the default make target
The default make target is the first target in the Makefile. In our case it is 'all'. Previously, 'all' in turn ran build-all and test-all (actually depended upon them). Our user instructions are to run 'make' and so this would be what they saw per default.
The average user that wants to use nso-docker will run it stock, i.e. have no local modifications and so it is excessive to run the test suite per default. We can expect that a user that is sufficiently skilled to modify nso-docker also understands the value of running the test suite.
I added a message to hint the user about the 'test-all' target.
Closes #109 (closed)