python: Added upm directory for python modules

* Grouped UPM python modules into upm directory, for example:
      /usr/local/lib/python2.7/dist-packages/upm
    * Updated UPM example import statements
    * Removed unused RPATH statements from UPM src CMakeLists.txt,
      currently build collateral contains an explicit RPATH which
      is stripped from the install collateral.
    * Converted python examples to work on both python2 AND python3
    * Added ctest for loading examples w/python3
    * Removed returns from swig macros
    * UPM python module use will change...
        Before:
            import pyupm_dfrph
        After:
            from upm import pyupm_dfrph
            or
            import upm.pyupm_dfrph
            etc...
    * This commit fixes #468

Signed-off-by: Noel Eck <noel.eck@intel.com>

examples/python/loudness.py

@@ -21,8 +21,9 @@
 # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
+from __future__ import print_function
 import time, sys, signal, atexit
-import pyupm_loudness as sensorObj
+from upm import pyupm_loudness as sensorObj
 
 def main():
     # Instantiate a Loudness sensor on analog pin A0, with an analog
@@ -36,7 +37,7 @@ def main():
 
     # This function lets you run code on exit
     def exitHandler():
-        print "Exiting"
+        print("Exiting")
         sys.exit(0)
 
     # Register exit handlers
@@ -47,7 +48,7 @@ def main():
     # corresponding analog voltage.
 
     while (1):
-        print "Detected loudness (volts): ", sensor.loudness()
+        print("Detected loudness (volts): ", sensor.loudness())
         time.sleep(.1)
 
 if __name__ == '__main__':