Point path to ~/.config/hub
Pull in github.com/BurntSushi/toml
Refactor to use toml for config

* Rename Credentials to Credential
* Use toml for config
Rename Config.DefaultCredential()
Fix cukes setup steps to use toml
One Credential
Use array of table for config format
Change config sample in test to reflect what's expected

We'll store the host name with scheme instead of the API endpoint
Match the new array of table TOML format
Add stub block for loading from YAML
Use current user's login for config user name
Fix OAuthAppURL
Change expectation from oauth_token to access_token
Add error formatting to authentication
Revert "Add error formatting to authentication"

This reverts commit 26540bba589ba1345289d43ec47c520e354119cd.
Use the right format for X-GitHub-OTP in dukes

See https://github.com/octokit/octokit.rb/blob/ab0404e0f1c6d36ed52c6e9c8c9734a5f14ec839/lib/octokit/error.rb#L155
More fixing of the right X-GitHub-OTP header
Make sure special characters work in cukes
Fallback to use fmt.Scanln
Fix config permission according to hub's cuke