Rename SITKLanguageOptions.cmake to sitkLanguagesOptions.cmake

For more consistent naming.

Change-Id: I1cbfc27751221a7515a972e5e37852a74787ee35
Enabling R by default if detected on the system

All tests are not passing with R enabled. The enum issue has been
resolved with SWIG 2.0.11.

Change-Id: I9a435fab1ebf0bcddf435ec35475278ba98ade85
Merge topic 'SIMPLEITK-473_EnableRByDefault' into next

2c4b19aa Enabling R by default if detected on the system
0cbb55e6 Rename SITKLanguageOptions.cmake to sitkLanguagesOptions.cmake