Openfoam cleanup

These are updated versions of the OpenFOAM EasyConfig and patch files.
It goes together with PR https://github.com/hpcugent/easybuild-easyblocks/pull/436 for the OpenFOAM EasyBlock.

The main changes are:
- Support for OpenFOAM 2.0.1
- Support all the MPI toolchains in the same way
- Properly define `FOAM_MPI` variable (its value is used as a subdirectory name to put the MPI-based libraries in)
- Cleanup the SCOTCH include and library paths
- Make sure to find SCOTCH if provided as a dependency in EasyConfig, and not compile the one shipped in ThirdParty tarball
- Make all the EasyConfig and patch files uniform 

It has been tested and seems to build correctly for OpenFOAM (2.0.1, 2.1.1, 2.2.0, 2.3.0) built with goolf (1.4.10) and ictce (5.3.0). `OpenFOAM-Extend` and `iqacml` toolchain have not been tested.

Please review and let me know if you have any comment so I can continue the same way for OpenFOAM-Extend.