[UIMA-3969] add dependency on Jackson to uima core to support json serialization

git-svn-id: https://svn.apache.org/repos/asf/uima/uimaj/branches/2.6.0-json@1617348 13f79535-47bb-0310-9956-ffa450edef68
[UIMA-3969] add Json content handler that wraps Jackson impl, supports pretty printing in a style useful for UIMA data

git-svn-id: https://svn.apache.org/repos/asf/uima/uimaj/branches/2.6.0-json@1617349 13f79535-47bb-0310-9956-ffa450edef68