SHA environment

[andyneff]

Get output of environment variables (and local variables?) and sha them

• Determine list of variables that shouldn't be include, like UID, pwd, , BASH_SOURCES, LINENO, BASH*, etc...
• Sha variables and values

This is a stepping stone to running docker-compose config once, and caching the result. The environment can be used to determine cache miss. Since Just-docker-compose creates a randomly named file and used env vars to generate it, the command executed is not a sufficient cache miss check, it will always be different or changing env vars will cause different behavior. And its always posssible that multiple calls to Just-docker-compose will have different environments. So the args to Just-docker-compose + env sha should make a decent cache miss check