Unable to use configuration with URI Parts

[juicegit]

Currently, if I specify the Rabbit Host Parts via topology config, I get a a NPE when it is trying to configure the connection. It looks up HA Hosts and fails because it is null (not specified). If I use "" for Hosts, it fails again trying to use the value as a host. The Config.getFromMap() needs to check for null before trying .toString().

I fixed this in a pull request.

[jnioche]

Same issue. It is currently not possible to configure it via the topology config unless you define rabbitmq.ha.hosts, see [https://github.com/ppat/storm-rabbitmq/blob/master/src/main/java/io/latent/storm/rabbitmq/config/ConnectionConfig.java#L176]

Any reason not to fix it?