reading config value from system env in common test

[Aeolus]

Hello everyone,

Merry Christmas to all! As a newbie to Erlang, I wonder if common test
could read config value directly from system shell instead of from a
config file. Actually there is one mentioned in the doc,
"CT_INCLUDE_PATH", but maybe we could have more like CT_SUITE_PATH,
CT_LOG_PATH.

Thx.

//Aeolus