Update printer.py
Update printer.py
Update printer.py
Added ability to print barcodes

http://www.adafruit.com/datasheets/A2-user%20manual.pdf
Update printer.py
Added ability to print barcodes

http://www.adafruit.com/datasheets/A2-user%20manual.pdf
Update README.md
Changed Heat settings for faster printing.
Few fixes to documentation styling and docstrings