Multiple changes related to building the vdiv c source w/c example.
* Renamed GroveVdiv to vdiv (all cases) throughout source, examples,
directory names, and documentation.
* Added C source.
* Tested C sensor code on edison
* Updated CMakeLists.txt for examples-c to build from
<sensorname>-c. This was a small change to get c examples to build
for sensors in which the C++ does NOT wrap the C.
* Added C example for vdiv.
Signed-off-by: Noel Eck <noel.eck@intel.com>
