nla/amberdb — pull request #146 by shuangzhou (2014-05-29 06:58:00+00:00)
Title: Refactor models

Updated the following:
- created a static ObjectMapper per Work and Copy instance.
- provided access to auditing fields via AmberTransaction, and an AmberTransaction instance can be retrieved from any Node.
- promoted local system number to Node.
- added other metadata fields in the WP1_WP2 package spec as required.