Add more methods for API so it can interact better with common torrent tracker scripts

[josecelano]

Parent: #137

Add more methods for API so it can interact better with common torrent tracker scripts:

• GET /api/peers/:peer_id: Return all peers with selected peer_id and include info_hash + peers stats for easier data manipulation.
• GET /api/peers/:ip: Return all peers with selected ip and include info_hash + peers stats for easier data manipulation.
• GET /api/peers/:priv_key: Return all peers with selected priv_key and include info_hash + peers stats for easier data manipulation.
• GET /api/key_status/:priv_key: Check if priv_key is used by multiple IP addresses and return number | false to check if someone is sharing key

Originated by @dev1z