Rdbms dyn var (second try)

RDBMS with all components to do work. Need tests to make sure some components, integration and specific scenarios work fine. We could define some complex test scenarios to evaluate it and create RFE and issues for things we need to do (or fix).

PRs:
core->https://github.com/lightblue-platform/lightblue-core/pull/151
mongo->https://github.com/lightblue-platform/lightblue-mongo/pull/14
rdbms->this (ignore the old https://github.com/lightblue-platform/lightblue-rdbms/pull/32 )
rest->https://github.com/lightblue-platform/lightblue-rest/pull/7