get_author_info(): Encode using PREFERRED_ENCODING rather than str()

Our version of check_output() returns Unicode strings.

For Python 3.x, os.environ works with Unicode strings, so everything
should be OK.

But for Python 2.x, os.environ works with byte strings, so we have to
encode the output of check_output() to bytes.  str() can do the job
only for ASCII characters.  For non-ASCII, we need
s.encode(PREFERRED_ENCODING).

So, add a function env_encode() that does this encoding.  Include two
versions: one for Python 2.x and one for 3.x.  Change
get_author_info() to use this encoding function instead of str().

This should fix issue #62.
Include some non-ASCII characters in the test repository metadata
Merge branch 'issue-62'

Correctly encode strings that are to be written to the environment.
This fixes #62.