Small test set for release

 - Only three tests are done: explosion, quadpole and quadpole with
   NetCDF. The last one is omitted, if NetCDF is not found.
 - The tests are failing, if the L2 misfit is larger than 1e-8, which is
   strict, but this is not a regression test anymore
 - Actual test files need to be committed, has to be done by Eric Heien.