I solved this by downloading the base64 library from forum here and extracting it to the arduino sketch folder i was working in and changing the include to from this
#include <Base64.h>
to This
#include "Base64.h"
not the best solution but im working in arduino 1.6.4! Also remember arduino can have two library folders and base64 can conflict if in both! also I found base64 references in the iot code conflicting! Make sure you find a combo that works!
Copy your arduino sketch and the contents of the base64.zip to this new folder remember arduino wants the sketchname to match the folder name
if that doesnt work i would uninstall arduino delete and residual folders and start over it will work! Or atleast it did for me!