Naming scheme for the underlying toolkit

[gigapod]

Use 'sfe' for the underlying object naming pattern.

Namely sfe[ObjectName

[edspark]

Changed all class names to include Sfe: SfeBus, SfeI2C, SfeSPI.

[edspark]

I think I'm leaning towards using "Arduino" or some abbreviated version of it for the I2C and SPI Classes since that's what they're tailored for. This would be in addition "Sfe" I think.

[gigapod]

This is done