Improve license storage

Currently Confluence stores the license details in the confluence.cfg.xml file, which is stored locally on each node.

When ever a license is installed on a node, the license details need to be distributed to each of the other nodes to be installed and stored in the confluence.cfg.xml file.

Prior to Confluence 5.6, license changes were not propagated across nodes (a bug). In Confluence 5.6, license changes are propagated to other nodes using the cluster event InternalLicenceUpdatedEvent.

The problem is that if a node is not active when a license is installed, it will not receive the cluster event InternalLicenceUpdatedEvent.

A more robust mechanism needs to be implemented, that handles nodes being down. Initial suggestions are:

• Store the license details in the shared home directory, and not the confluence.cfg.xml file. This will require cluster locking when updating the license details. Will also need to broadcast the cluster event InternalLicenceUpdatedEvent.

• Use the Journal service to propagate changes. Advantage is that the license details are still stored in the confluence.cfg.xml file. The downside is that license changes are not immediate. Not an ideal solution, but mentioned as a brain dump.