M5core2 - Add shudown/led1 command and battery level

[EnricoFerro]

Add additonal command for M5Core2:

This commands ares:

• poweroff or shutdown
• led1

Add the Battery Level in statusupdate

Prerequisite for this modify is the merge of https://github.com/fvanroie/M5Core2/pull/1

[fvanroie]

Thanks, I will check this PR when 0.6.3 is released

[Aaroneisele55]

@EnricoFerro thanks for adding this, merging it would also solve my Issue #490