Created two example SPI Programs

Two example SPI Programs for communicating with digital pot.
DigitalPot.cpp is a more complex menu driven program for writing to a
SPI pot. DigitalPotLEDFade.cpp is a very simple example program for
fading an LED using the digital pot.
Commented examples and added README

Updated main README, and added new README for SPI examples explaining
implementation, building and usage. Also, commented example programs so
it is easy to understand what is going on.
Spacing Issues

README now has proper spacing
More README fixes

Still figuring out GitHub READMEs
Bash Code

Fixed Bash formatting in README
Bash Formatting

Finally got bash formatting to display properly
Capitalization Issues

Fixed some formatting again
Added more comments

All examples are fully commented, README completed
Merge pull request #19 from wizard97/master

Digital Pot examples are done