* Move GitHub API module to utils/github.rb.

* Move curl method to utils/curl.rb.

* global: use long curl arguments and an array.

This makes the code more self-documenting.

* utils/curl: support reading curl's output.

* utils/github: use curl instead of open-uri.

It has far better proxy support.

* pull: set Homebrew user agent.

* gist-logs: remove trailing whitespace.

* gist-logs: use first instead of [0].

Easier to read.

* gist-logs: use curl-based GitHub.open method.