Adafruit MCP23008 Replacement

[ICE9-Andy]

README to be updated to new Adafruit library (Adafruit MCP23017) as the MCP23008 is depreciated.

[ICE9-Andy]

This does have knock on effect for mona_esp_lib which calls this older header.

The current workaround is to simply install the depreciated MCP23008 library.