[core] Fix error handling in kt_renewer.py for python3
[core] Fix error handling in kt_renewer.py for python3

On python3, if kinit fails to renew then the kt_renewer.py dies due
to a error handling logging not supporting binary strings.

cloudera/hue,kawamon/hue,cloudera/hue,cloudera/hue,cloudera/hue,kawamon/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,kawamon/hue,cloudera/hue,kawamon/hue,kawamon/hue,kawamon/hue,kawamon/hue,kawamon/hue,cloudera/hue,cloudera/hue,kawamon/hue,cloudera/hue,cloudera/hue,cloudera/hue,kawamon/hue,kawamon/hue,kawamon/hue,kawamon/hue,kawamon/hue,kawamon/hue,cloudera/hue,cloudera/hue,kawamon/hue,cloudera/hue,kawamon/hue,cloudera/hue,kawamon/hue