Update platform version to 1.8.1

Author: facchinm

platform.txt

@@ -19,8 +19,8 @@
 # For more info:
 # https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5---3rd-party-Hardware-specification
 
-name=Arduino SAMD New Boards
-version=1.6.28
+name=Arduino SAMD (32-bits ARM Cortex-M0+) Boards
+version=1.8.1
 
 # Compile variables
 # -----------------