Dividing Builder-API by Identity version

[auhlig]

As discussed in #666 this introduces the BuildersV2 and BuildersV3 to make it less likely to get confused by the 2 different Identity versions.

What do you think @gondor , @dhague ?

[dhague]

As discussed with @auhlig via PM just now, this idea of using Builders.<object>() for everything except Identity, where we use BuilderV2.<object>() and BuilderV3.<object>() doesn't feel quite right.
A better approach might be to stay with Builders.<object>() which would always use the latest version of an API (and a point release of OS4J whenever this changes), together with Builders.<service>().<object>() when a specific version is required.
This would give, for example:
Builders.user() creating a V3 user (in the current 3.0 release of OS4J)
Builders.identityV3().user() creating a V3 user regardless of OS4J release (>3.0)
Builders.identityV2().user() creating a V2 user regardless of OS4J release (>3.0)

This same pattern can then be used to support different versions of the other OpenStack services, and has the advantage that users of OS4J v3.0 would not have a breaking change when using V3 user objects.

[gondor]

@auhlig @dhague I agree with the Builders.<service>.<object> approach. I was thinking about it when I was getting ready for work and have V2 and V3 builders felt odd to me and would impose lots of breaking changes in the future. I like rooting it to the service based on the version of the service being used. Well promote less breaking changes.

[vinodborole]

Builders.<service>.<object>
makes more sense

[gondor]

@auhlig @dhague - I know this is a PR :) But wanted to introduce @vinodborole who made a comment above. He's been a big contributor as well. Do you mind also reviewing his latest PR which is targeted for V3 - PR #671 . @vinodborole - Darren and Arno did the V3 work, infact built the whole 3.0.0 release.

[vinodborole]

@gondor Thanks for introducing me to the team; its a privilege working with you guyz. Let me know what you think about my PR;

[wumingcheng]

@auhlig when does the new version publish, two weaks has gone.And don't forget to amend the bug of #679,

[gondor]

Currently its done manually by me. Working on integrating merged changes to deploy new snapshots via Travis CI.

[auhlig]

Hey @gondor, @dhague, @vinodborole,

I added commit b269507 implementing what we discussed. I also extended that pattern to the other services. Comes with groovy tests. Let me know what you think.

[vinodborole]

LGTM

[gondor]

LGTM - great job!