Update README.rst
cli: Check that the stream name exists before attempting to resolve it's true name.
cli: Split the utils module into a package.
cli: Improve the progress status when writing to a file.

- Display the bytes written in a more human readable format.
- Add elapsed time.
- Add average download speed.

Resolves #462.
Merge branch 'feature/progressbar' into develop
plugins.twitch: Friendlier error when failing to seek into a muted chunk.

Resolves #485.
cli: Print some useful info when interrupted.
docs: Add info about installing into a virtualenv.

Resolves #401.
Update CHANGELOG.rst.
plugins.twitch: Fix validation bug.