Should have a read deadline on the API and Admin server

[pauldix]

Many clients that connect to InfluxDB keep alive their connections and then don't reuse them. This ends up opening many thousands of connections to Influx and causing problems. We should timeout on Reads after a certain amount of time. I think 5 seconds is a reasonable default with the ability to override it in the configuration.

For reference see http://stackoverflow.com/questions/10971800/golang-http-server-leaving-open-goroutines and https://code.google.com/p/go/issues/detail?id=4676

[pauldix]

This is a dupe of #421