Don't decode str to utf-8 for param enum

This is causing a traceback in python3.3 because param.enum is already a
str, which has no method decode in python3.  In python2, param.enum is
already a unicode object so we don't need to decode to utf-8 either.
Merge branch 'develop' of github.com:boto/bcdoc into develop
Bumping version number.
Merge branch 'release-0.4.1'