allow to set env-filename via env vars
Do not use aliases for `cp` (as with `grep`)

Given an alias `cp='cp -i'`, autoenv_deauthorize_env would ask for
confirmation.
Merge pull request #69 from blueyed/use-cp-command

Do not use aliases for `cp` (as with `grep`)
Merge pull request #68 from mysz/custom-env-filename

allow to set env-filename via env vars