Add building hello world to the travis build.
Add building hello world to the travis build.

SRI-CSL/OCCAM,ashish-gehani/OCCAM,SRI-CSL/OCCAM,ashish-gehani/OCCAM,ashish-gehani/OCCAM,SRI-CSL/OCCAM,ashish-gehani/OCCAM,SRI-CSL/OCCAM,SRI-CSL/OCCAM