Feature Request: Support for connectionLifetime option

[shamasis]

The idea is to destroy a connection from a pool once it has stayed connected for a specified duration of time.

• we need to accept this option
• we need to listen to the connection event in pool and set the current time in it
• listen to the release event of pool and check if current time is - created time is > lifetime option.
• if yes to above, then do connection.destroy()

Ref:
mysqljs/mysql#1872 (API to destroy)
https://github.com/mysqljs/mysql#pool-events (Pool Events)
https://github.com/postmanlabs/sails-mysql-transactions/blob/develop/lib/db.js (module where the read-only pool cluster is created)
https://github.com/postmanlabs/sails-mysql/tree/master-postman/lib/connections (location where writeable pools are created)