Add porcelain for 'status'.
Add test to make sure unmodified files don't show up in get_unstaged_changes.
Move logic for creating blog from path to dulwich.index.
Use the print() function in Makefile.

Use the print() function rather than the print statement in the
Makefile.
print(): Switch from statement to funtion.
Fix octal literals.
Use io module instead of file.
Use int division `//` insted of float division `/`.
Make next methods available as __next__.
Use assertEqual rather than assertEquals as the latter is deprecated.
Use for loop instead of map when not iterating.

In PY3, map returns an iterator, so the funcion never gets called.
Correctly handle binascii.Error.
In Protocol.read_pkt_line, assert the length of the data read matches the length prefix.