utilstest.py - fix pyflake suggestions
macro resolving for hostaddress fixes

If user request macro $HOSTADDRESS$ and no address
is configured, we immitade nagios behavior and
return HOSTNAME instead
Utils.AttributeList() - now aware of "null"

If "null" is specified as an attribute, treat it as an empty list.
Merge branch 'master' of github.com:pynag/pynag