This patch makes sure that all references to the name of the software is
ganeti-htools, not simply htools.

This doc-patch adds copyright and license information to (hopefully) all
needed files.

This patch moves the test declaration into QC.hs, so that test.hs has to
be modified only when we add a new test category.

This is more of an exercise in QuickCheck than strong testing.

This patch adds a QuickCheck-based test infrastructure and initial tests
based on it. The PeerMap module has a 100% coverage ☺️

Side-note: one has to read the source of QuickCheck to see how to use it
(especially the Batch submodule), the docs are not enough…