Upgrade to Jackson 2 complete

I have just pushed the changes (and they are built into the latest 1.1.0.BUILD-SNAPSHOT builds) for Spring Social to depend on Jackson 2. (https://jira.springsource.org/browse/SOCIAL-362)

Note that this was a rather sweeping change to the API bindings. Thankfully, there's a rich collection of unit tests to help me feel confident that everything is still working fine. But there still exists a chance that the upgrade to Jackson 2 will have broken something.

I urge everyone to try out these new builds and test them thoroughly. If you find anything out of place, please create a bug issue in JIRA for the project you find the issue in...

- https://jira.springsource.org/browse/SOCIAL
- https://jira.springsource.org/browse/SOCIAL-FB
- https://jira.springsource.org/browse/SOCIAL-TW
- https://jira.springsource.org/browse/SOCIAL-LI
- https://jira.springsource.org/browse/SOCIAL-TI
- https://jira.springsource.org/browse/SOCIAL-GH

Also note that this required a change to AbstractOAuth1ApiBinding and AbstractOAuth2ApiBinding. If there are any community-led projects that are depending on the latest snapshots or that will depend on the 1.1.0.M3 release when it is pushed, those projects will need to be updated to use Jackson 2 as well. (I'll reach out as much as I can to the community project leaders to let them know of the change, but please tell me if you run into trouble and I'll try to get them involved or help them out to expedite the upgrade.)