Encoding environment variables [JIRA: CLIENTS-864]

[lukebakken]

The following environment variables influence the default encoding of the Python interpreter:

$ declare -x|fgrep -i utf
declare -x LANG="en_US.UTF-8"
declare -x LC_ADDRESS="en_US.UTF-8"
declare -x LC_COLLATE="en_US.UTF-8"
declare -x LC_CTYPE="en_US.UTF-8"
declare -x LC_IDENTIFICATION="en_US.UTF-8"
declare -x LC_MEASUREMENT="en_US.UTF-8"
declare -x LC_MESSAGES="en_US.UTF-8"
declare -x LC_MONETARY="en_US.UTF-8"
declare -x LC_NAME="en_US.UTF-8"
declare -x LC_NUMERIC="en_US.UTF-8"
declare -x LC_PAPER="en_US.UTF-8"
declare -x LC_TELEPHONE="en_US.UTF-8"
declare -x LC_TIME="en_US.UTF-8"

These should be unset or set to C in the Makefile to "genericize" the encoding environment and simulate a wider range of end-user environments.

Inspired by PR #474