Add support for multiple UDP + JSON input plugins

[tpitale]

Support comes by way of [[input_plugins.udp_servers]] in config.
A single port will map to a single database.

• Update sample config to include [[input_plugins.udp_servers]] example
• Change configuration.Configuration to hold config for array of udp servers
• Change configuration.UdpInputPortString to accept a port int
• Modify udp.NewServer to accept listenAddress string, database string
• Modify server.Server struct to hold an array of udp.Server
• Modify server.NewServer to not create any udp.Server
• Update server.ListenAndServe to check and instantiate all instances of udp.Server

[tpitale]

I tried to run the build and tests locally. It said there was an error … but the only one it showed was that there was already a port bound on 8083. Maybe tests conflict with a run influxdb instance?

[tpitale]

I would perhaps like to add integration tests for this. If that's required, I will investigate and this can be a WIP.

[tpitale]

All tests pass locally. Had to shut down my local influxdb.

[tpitale]

Oh, question: is there a way to mark the old configuration pattern as deprecated if this udp_servers config is the way udp should be configured going forward?

[jvshahid]

Thanks @tpitale for contributing to InfluxDB. You may want to take a look at this commit (since this is your first go contribution) where I slightly modified the code to make it more idiomatic 9a6cc74.

[jvshahid]

@tpitale do you mind signing the CLA really quick. You can find it on our website http://influxdb.com/community/cla.html

[tpitale]

Signing now. BRB.

[tpitale]

Done.

[jvshahid]

Thanks