Integrate the openCFS hdf5 reader as CFSReader plugin

* is a modification of the plugin from gitlab.com/openCFS
* has a dependency hdf5 with c and hl api and boost filesystem
* reads hdf5 files with openCFS data format (usually called *.cfs)
* knows multiple regions, multiple steps and multiple solution types
* real and complex valued data
* used C++11 w/o parallelization