Extend tests

- Test that make clean works
- Test that the files that were expected to be created was
  created, not just that the make did not fail

Signed-off-by: Jonas Eriksson <zqad@acc.umu.se>
Merge branch 'more-tests-damnit' from zqad

Also make the syntax more Make oriented.

Signed-off-by: Nils Carlson <pyssling@ludd.ltu.se>