Strip --no-cache-dir for pip < 1.6
Strip --no-cache-dir for pip < 1.6

Closes #2738

foosel/OctoPrint,Jaesin/OctoPrint,foosel/OctoPrint,Jaesin/OctoPrint,foosel/OctoPrint,Jaesin/OctoPrint,foosel/OctoPrint,Jaesin/OctoPrint