Bug fixes:
- Fix behavior when passing a `dict` value as the default
to `env.dict` ([76](https://github.com/sloria/environs/pull/76)).
Thanks [c-w](https://github.com/c-w) for the PR.
Support:
- Document how to read a specific file with `env.read_env`
([66](https://github.com/sloria/environs/issues/66)).
Thanks [nvtkaszpir](https://github.com/nvtkaszpir) and
[c-w](https://github.com/c-w).