Include config.h if present
Merge pull request #23 from blattms/bugfix/issue-22

Patch includes config.h and fixes issue #22
added: sanity check specified isotropic materials

if we end up with too small/large poisson's ratio,
bail with an error message rather than crashing with a segfault
Merge pull request #25 from akva2/santiy_check_isotropic_materials

sanity check (rock-list) specified isotropic materials in elasticity upscaling code
change namespace from 'Dune' to 'Opm'

everything still compiles.
Merge pull request #26 from andlaus/dune_to_opm

change namespace from 'Dune' to 'Opm'