APIs for pull requests

Particularly these commands are desired:

• /api/v1/{user}/{repo}/pulls?status={open/closed}&id={id} - retrieves the list of pull requests (or one pull request)
• /api/v1/{user}/{repo}/pull/{num}/files - retrieves the list of affected files for the pull request
• /api/v1/{user}/{repo}/pull/{num}/diff - retrieves the diff file for the pull request
• /api/v1/{user}/{repo}/pull/{num}/comments - retrieves the list of comments
• /api/v1/{user}/{repo}/pull/{num}/comment-submit - PUT submits a new comment