Recent changes need to bump the CMake version

[Andrew Davis]

Recent changes to the pymoab part notably, mean the minium cmake version should be 3.0 - https://stackoverflow.com/questions/7637539/how-to-split-strings-across-multiple-lines-in-cmake - due to mulitline comment use.

cmake_minimum_required( VERSION 2.8.12 ) from base cmakelists should be 3.0 instead

[Vijay M]

Thanks for submitting the PR.

[Vijay M]

This was resolved with changes in PR #407