update version to 1.7.7, and remove useless file.

Author: LynnL4

CHANGELOG

@@ -20,7 +20,7 @@
 # https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5---3rd-party-Hardware-specification
 
 name=Seeed SAMD (32-bits ARM Cortex-M0+ and Cortex-M4) Boards
-version=1.7.6
+version=1.7.7
 
 # Compile variables
 # -----------------