Merge pull request #2 from jaredmolson84/master

Add simple openCL demo program
Revert "Merge pull request #2 from jaredmolson84/master"

This reverts commit a0f17859a225bc5c98d56cdc931ea9e829b577ad, reversing
changes made to 4935e815e57ad1f906b9268dfa6240396566a178.

hello_world.cpp was clobbered by hello_world.cl.
Resolves #3. Move source files into src directory and update Makefile accordingly.