First release op eSalsa POP containing GPU code

This is the 1.2-GMD-beta release of eSalsa POP.

This release is the first to contain GPU code (CUDA) and has been used for the POP experiments experiments described in out paper "A distributed computing approach to improve the performance of the Parallel Ocean Program" (Submitted to Geoscientific Model Development).

Although the GPU code should work, but there is little documentation at the moment. This will be improved in the next version.