Add user notifications.
Support Repo Hooks API

see: http://developer.github.com/v3/repos/hooks/
added star/undstar/isStarred
Update README.md

Documented branch parameter for ´contents()´
Iterate over paged data sets

Some APIs do not honor the per_page API (at least for large values) and
require that we actually walk the links headers to pull all data.
Add additional github repo APIs

Implements
- listTag
- listPulls
- compare
Add getPull and listIssues APIs
Merge branch 'repo-features' of github.com:kpdecker/github into pull_reqs
Merge branch 'patch-1' of github.com:kekscom/github into pull_reqs
Merge branch 'master' of github.com:RayKwon/github into pull_reqs
Merge branch 'support-repo-hooks-api' of github.com:tricknotes/github into pull_reqs
Merge branch 'add-notifications' of github.com:FajitaNachos/github into pull_reqs
Merge branch 'auto-paging' of github.com:kpdecker/github into pull_reqs