Extra fixes for 2.0.1

Some additional fixes/improvements for the testing code.
-- make dist works now -- python tools/tester.py performs unit tests, most of them pass fine on ubuntu 16.04 ( after configure using ./configure --enable-applgrid --enable-apfel --enable-lhapdf --enable-mela --enable-apfelgrid --enable-hvqmnr )

==> I think after this merge we can go ahead with a test tag and final set of tests. -- on naf-xfitter -- on mac -- using different compilers ( clang, intel)