InstantDeserializer is not working with offset of zero +00:00 and +00

[kevinjom]

I am working on a project with Spring boot, and it uses Jackson as the json parse library behind to scene to parse http input message into Objects. And some of our clients will pass a timestamp string like this 2017-03-13T11:11:11.000+00:00, and I found that didn't work with current implementation of InstantDeserializer.java.

I am thinking if we can replace a zone offset of zero that is +0000 with Z, we probably should also replace +00:00 and +00 as well, because as I found in this Wiki page, they are also valid zero offsets.

I didn't find a CONTRIBUTION guide so I've made a quick change here, I am not sure if you guys are happy with that. If so, I'd like to make a request to fix it.

[kevinjom]

Well, I've created a PR #19 here.

[cowtowncoder]

Excellent, merged, will be in 2.9.0(-pr2)!