Update dependency list for the fallback script

# If this is not possible, please disable:

# PERFORM_IPV4_DIRPORT_CHECKS and PERFORM_IPV6_DIRPORT_CHECKS

#

# Needs dateutil (and potentially other python packages)

# Needs stem available in your PYTHONPATH, or just ln -s ../stem/stem .

# Needs dateutil, stem, and potentially other python packages.

# Optionally uses ipaddress (python 3 builtin) or py2-ipaddress (package)

# for netblock analysis, in PYTHONPATH, or just

# ln -s ../py2-ipaddress-3.4.1/ipaddress.py .

# for netblock analysis.

#

# Then read the logs to make sure the fallbacks aren't dominated by a single

# netblock or port

# netblock or port.

# Script by weasel, April 2015

# Portions by gsathya & karsten, 2013