Restore Python 2.6 compatibility (#10 and #11)
Restore Python 2.6 compatibility (#10 and #11)

Python 2.6 breakage noticed on Travis CI:
 - https://travis-ci.org/xolox/python-humanfriendly/builds/163513409

Refer to issues 10 and 11 on GitHub for details:
 - https://github.com/xolox/python-humanfriendly/issues/10
 - https://github.com/xolox/python-humanfriendly/issues/11

xolox/python-humanfriendly,xolox/python-humanfriendly