Insert retry number

Hi!, We're using influxdb on a project, and when we had a problem connecting to the host, influxdb was trying to connect countless times. This is a problem because the server remains waiting for reply.  We decide to set up the gem for receiving the :retry param as a number and not as a boolean. In this way influxdb will try to connect :retry times.

By default influxdb will try to connect 3 times, and if you pass -1 it will try to connect forever until it gets a response.