Updated core files including libsam to Arduino 1.5.7
RTOS core: Based on Arduino 1.5.7 to me modified as needed
Updated bords.txt, Adding board for v0.333 and updating names on v0.2
Readme update as we now require 1.5.7 IDE to build
Merge pull request #47 from emfcamp/core-update

Core and variants update for resolves #27