Spark

Spark.io support
Reviewing this again I've realized that HardwareSerial should no longer be included in Firmata.cpp anyway. Stream.h should be included in it's place and then HardwareSerial.h should be included in StandardFirmata.ino before the Firmata.h include. If someone creates an ethernet version of StandardFirmata they would include Ethernet rather than HardwareSerial. So someone should try to get [Stream](https://github.com/arduino/Arduino/blob/ide-1.5.x/hardware/arduino/avr/cores/arduino/Stream.h) included (and properly integrated) in spark/core-firmware. I'll make the necessary updates to Firmata.