CMake 2.8.5 or higher is required

make with error for the lower version:

Linking CXX executable ../../bin/jsoncpp_test
/bin/sh: $<TARGET_FILE:jsoncpp_test>: command not found
make[2]: *** [bin/jsoncpp_test] Error 127
make[1]: *** [src/test_lib_json/CMakeFiles/jsoncpp_test.dir/all] Error 2
make: *** [all] Error 2

due to 
http://stackoverflow.com/questions/5410164/how-do-i-use-a-targets-path-in-add-custom-command-in-cmake#comment6139682_5410794
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9ad6fc6..ee2a8bf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-CMAKE_MINIMUM_REQUIRED(VERSION 2.6)
+CMAKE_MINIMUM_REQUIRED(VERSION 2.8.5)
 PROJECT(jsoncpp)
 ENABLE_TESTING()