Commit less generated output

I'd like to commit less auto-generated output, since it makes diffs much larger and more confusing.

We currently generate the changelog, shell completion scripts, readme, book, and man pages.

The readme must be present in master to render on GitHub, so that can continue to be committed.
The changelog is tricky to get right, so we can continue to commit that, so committers see in the diff what it's going to look like.
[x] The man pages require the help2man program, so those can only be skipped if the help2man program can be installed on windows.
[x] The completions scripts don't need to be committed, as long as they're still built before running bin/package.
[x] The book dosn't need to be committed, as long as it's built before deploying to github pages.

casey / intermodal