2.0.0

Changelog

39bdd50 Integrate GoReleaser for easy release management.
dadd5c8 Support a global environment variables file.
548565f Add a dependency on github.com/mitchellh/go-homedir.
76b51f7 Clear out the environment before loading context specific variables.
20ad358 Add support for multiple environment files.
f9188ed Support commented-out lines in environment files.
490929a Adjust environment file parsing functionality.
3db0715 Update the copyright notice.