merge from huaweiwx

remove unused doc

remove the dup c and head file

remove useless file

Fix serial issue

Add initial Lowpower support
Fix some example
Add new example
Update FreeRTOS library
Add Lowpower example
Remove doc file

Fix some bug on upload tool

Remove doc file

Modified file to fit for the BoardManager

Fix bug when the Boardmanager install this package
Move gcc toolchain into {build.system.path}/gcc
Move tools into {build.system.path}/tools

Add Low Power Driver

Add arm toolchain