Vector Addition with Raja

Performs vector addition in parallel, utilizing Raja for within-node and
Charm++ to run multiple processes (i.e. logical nodes) that can be executed
in a distributed memory environment.

Default Raja execution is OpenMP, but can be changed to use the available
GPU devices instead (with CUDA) by providing '-g' as a command line argument.

Requires Raja to be built with GPU support.
e.g. From Raja source folder,
> mkdir build && install
> cd build
> cmake -DENABLE_CUDA=On -DCMAKE_INSTALL_PREFIX=<path to RAJA install folder> ../
> make -j
> make install

Path to Raja install folder and GPU compute capability should be set in Makefile.common.
