Make zk-bom an independent repo and establish a jenkins job to publish it automatically

User Story

To avoid manual mistake, make zk-bom an independent repository under zkoss/ and establish a jenkins job to publish it automatically.

Acceptance Criteria

1. move zk-bom to an independent repository under zkoss/
2. write a jenkins job to publish zk-bom: if there is any version need to update(check once per day).

Details