Merge pull request #1097 from SWIFTingAround/master

Set cmake-policy CMP0048 to NEW

CMakeLists.txt

 # increase to 3.1 once all major distributions
 # include a version of CMake >= 3.1
 cmake_minimum_required(VERSION 2.8.12)
+if (POLICY CMP0048)
+  cmake_policy(SET CMP0048 NEW)
+endif()
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 
 # Adhere to GNU filesystem layout conventions