Remove Python 2 compatibility code

[patricksanders]

We're no longer compatible with Python 2, so we can remove all of the compatibility workarounds.

For example:

aardvark/aardvark/manage.py

Lines 24 to 32 in 5926d03

	try: # Python 2
	raw_input
	except NameError: # Python 3
	raw_input = input
	try: # Python 2
	unicode
	except NameError: # Python 3
	unicode = str

This block can be removed and the code updated to use str and input.