Added Firmware for CMKC65 Keyboard to boards/ folder.

[thomasdevine01]

The CMKC65 is a board created by a local keyboard club at California State University, Chico for a limited first round group buy. The board is going to be having a second group buy later this year. This board features an IO Demultiplexer, OLED support, and a Rotary Encoder. The board is open source, and it is welcome to revisions or pull requests

[xs5871]

1. "Replacing" parts of the firmware code base as a part of the "configuration" is obviously a terrible idea. If there are missing features, we can incorporate those. If your hardware design needs some unique custom code for some reason, you can "patch" those in with custom child classes.
2. We strongly recommend the display extension over the peg oled one.
3. Don't forgen to run make lint to pass automated code QA.