Failover URLs in Datasource

Hello,

we have Bug #1039 which means that the cool feature of failover urls
does not work using DataSources; and not for a big reason but only
because the data source assumes a single port number instead of
multiple.

Since we use Wildfly with postgres in production I have a big interest
in getting this to work, so I tried to discuss this in the github issue,
sent a (trial) patch in the hope to progress things, then submitted
PR #1457, but have gotten no response nonetheless, so now I post here
in the hope to find a developer interested in fixing Datasources with
failover urls.

The point is, while I am a seasoned Java and EE developer, I have no
experience whatsoever in the pgjdbc code base and can't tell if my
approach or PR is a good solution, only part of a bigger thing
or utterly naive.

I would think the PR is complete except the coding convention stuff.
(Actually, can not a regular developer with the correct settings in
his IDE fix this in 1 second (CTRL-SHIFT-F or something) rather than me
doing this tediously by hand? But anyway I'd do it if I got some
encouraging feedback at all).
Also I have no idea if the travis "openjdk7" fail means anything!?

Please talk to me :-) at
https://github.com/pgjdbc/pgjdbc/issues/1039
https://github.com/pgjdbc/pgjdbc/pull/1457

Thanks Tom.