[ci skip] Never use easy_install if you can avoid it. The correct way to...

[ci skip] Never use easy_install if you can avoid it. The correct way to install pip is with the official script.

README.md

@@ -119,9 +119,9 @@ These instructions are suitable for a clean **Ubuntu** or **Mac OS X** setup. Th
         brew install hdf5 --with-mpi
         brew install fftw --with-mpi
 
-    Install the python package manager by calling
+    Install the PyPi package manager pip by downloading the [get_pip.py](https://bootstrap.pypa.io/get-pip.py) script and calling
 
-        sudo easy_install pip
+        python get_pip.py
 
 2. Install the necessary Python packages using `pip`: