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/temperature.py

@@ -1,3 +1,4 @@
+from __future__ import print_function
 # Author: Brendan Le Foll <brendan.le.foll@intel.com>
 # Contributions: Sarah Knepper <sarah.knepper@intel.com>
 # Copyright (c) 2014 Intel Corporation.
@@ -22,20 +23,20 @@
 # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 import time
-import pyupm_temperature as upm
+from upm import pyupm_temperature as upm
 
 def main():
     # Create the temperature sensor object using AIO pin 0
     temp = upm.Temperature(0)
-    print temp.name()
+    print(temp.name())
 
     # Read the temperature ten times, printing both the Celsius and
     # equivalent Fahrenheit temperature, waiting one second between readings
     for i in range(0, 10):
         celsius = temp.value()
         fahrenheit = celsius * 9.0/5.0 + 32.0;
-        print "%d degrees Celsius, or %d degrees Fahrenheit" \
-            % (celsius, fahrenheit)
+        print("%d degrees Celsius, or %d degrees Fahrenheit" \
+            % (celsius, fahrenheit))
         time.sleep(1)
 
     # Delete the temperature sensor object