Bump Jackson to latest (2.3.1)

Currently, Nx Core has _two_ Jacksons included:
* core uses "ancient" 1.9.x
* Yammer MetricsServlet pulls in "old" 2.1.x

This interferes a much with Kazuki for example, that is incapable to run with 2.1.x as it seems (at least I got ugly errors with Jackson 2.1 and 2.3 classes mixed, latter is Kazuki plugin dependency).

Note: MUST have these changes
https://github.com/sonatype/sisu-jacksbee/pull/1
https://github.com/sonatype/sisu-siesta/pull/13

CI
TBD