Update Firmata to version 2.3.6

Firmata 2.3.5 contains a bug that may affect users of some Firmata client libraries. This pull request updates to Firmata 2.3.6 which fixes the bug. Also updated the properties file and added the readme to extras.

I have a newer version (2.4.0) in the works that fixes some long standing bugs and frees up some memory but want to get 2.3.6 in before Arduino 1.5.3 is released (just in case that happens before Firmata 2.4 is ready).