Updated UPM cmake to build both python2/3 modules if the necessary
python libs are available.
* Removed BUILDPYTHON3 cmake option in favor of building both
versions
* Added cmake module to find both python2 and python3
* Added macro which can be called from per-sensor cmake files
to add dependency libraries via target_link_libraries as well
as swig_link_libraries (for java, nodejs, and python)
* Python2 is required for python documentation builds
* Cleanup of python usage throughout UPM cmakelists.
* Make find_package for Node required. Removed check for NODE_FOUND
(which should have been NODEJS_FOUND) in favor of REQUIRED.
* The cxx and .py wrapper files get generated in python2/3 (instead
of the same directory). It appears these files are identical,
however since the targets can be built in parallel it's safer to split
them out.
* Updated all cmake dependencies related to building documentation.
* Removed unused classname from cmake files
Signed-off-by: Noel Eck <noel.eck@intel.com>
