Fixed test_linearsolver for the official 2.2 release.

This release does neither support KAMG nor FastAMG. Therfore
this patch deactivates test these preconditioners.
Fixes the laplacian.

As we do not represent dofs on the boundary, we need to make sure that all diagonal
values are 4.
Increase verbosity such that we see the actual solve
Merge pull request #539 from blattms/fix-pr-532

Fixes issues in pull request #532