Add support for the /hooks endpoint

/hooks lists the supported hooks for GitHub
and their parameters
Merge pull request #336 from danmcclain/master

Add support for the /hooks endpoint
merge http params for application auth
Use the stack for .root because it's not a :snowflake:
Merge pull request #338 from rmetzler/feature/dont-forget-application-authentication-bug-337

merge http params for application auth
Merge branch 'master' of https://github.com/octokit/octokit.rb into pass-app-creds-to-root
Merge pull request #339 from octokit/pass-app-creds-to-root

Use the stack for .root because it's not a :snowflake:
v2.6.0
Release 2.6.0