Fix a bug on python 3.4 due to lack of PEP-461
Fix a bug on python 3.4 due to lack of PEP-461

Python < 3.5 does not support PEP-461 (%-formatting of bytes object),
so imgcat was not working at all on those versions.

To support legacy python versions, do not use %-formatting.

wookayin/python-imgcat