Add Matthew Hooker as a contributor
Change open file mode from `rwb` to `r+b`

This manifested as a bug on FreeBSD.

The goal is to get a readable, writable file in "binary" mode (not
it's likely Windows is going to work).  But, spelling that mode "rwb"
seems to be platform specific, and is not documented by Python
probably for these reasons.

This mode is not documented by Python, which prefers "r+" to spell out
this intention:
http://docs.python.org/2/tutorial/inputoutput.html#reading-and-writing-files
Add Petar Radosevic as a contributor