Removed "label" properties which no longer have any function.
Labels are still used as layer names and as identifiers for sending
behaviors between sides of a split keyboard, so those have been left
alone for now.
* Add Contra Shield (#1)
* Add bluetooth control layer to contra keymap (#2)
* fix contra keymap issues
* add bluetooth control layer
* clean up contra files
* add contra.conf file
* add missing bracket for default_layer
* update copyright year to 2021
* add contra metadata file
* refactor pro micro overlay for new syntax