Overhaul of the README to be more straightforward

Raspbian has updated and that makes the install procedure much more
straightforward. I think this is exactly what I have done a couple times
now so hopefully it actually works.
Now flushes the RX buffer twice.

This is based on the errata sheet and both the TinyOS and Contiki
implementations.

Fixes issue #15.
removing whitespace at end of lines
revamped printk system

Changed ioctl to allow for variable amount of debug printing at
cc2520.ko runtime. This way applications can completely turn off debug
output, or enable full debug output without having to recompile the
module.

Defaults to INFO level printing, as before.
removing old printk #defines
Merge pull request #18 from bradjc/printk

Revamped Debug Printk
Merge pull request #16 from bradjc/readme

Overhaul of the README to be more straightforward
Merge pull request #17 from bradjc/2flushrx

Flush The RX Buffer Twice