[MINOR] Misleading minimum required version of CMake

In most of CMakeLists.txt files, I can find following lines, which may be misleading.
```
cmake_minimum_required(VERSION 2.8.9)
cmake_policy(SET CMP0048 NEW)
```
Polices are available in CMake version > 3

## Steps to Reproduce
use cmake with  2.8.9 < version < 3

## System Information
centos 7, Cmake 2.9.13 

Regards, 
Rafał 