* Add support for S7 Elephant
A high-end 70% custom keyboard designed and produced by jacky from Geekhack.
* Polish S7 Elephant code
Implement drashna's suggestions:
- specify bootloader
- remove unnecessary defines
- use led_set_user() for LED logic
* Correct info.json and s7_elephant.h
Correct info.json and s7_elepant.h to follow QMK convention and fix a
missing curly bracket.
