Updated Java Agent project version in preparation for next release.

AME-3033: CR-3072: Update JEE agents to follow common license packaging approach

Fix for OPENAM-3492, review CR-2790. A cleanup of the Maven build process for the JavaEE policy agents.

Updating agent version number to 4.0.0-SNAPSHOT

Fix for OPENAM-2714, review CR-2107. Update agentadmin script to escape variables to avoid being replaced incorrectly during maven build process.

Added missing build_date.js files to the target dir of each distribution. These are used by the downloads page. Part of work for AME-2042.

Rework distribution builds to have a separate version per agent rather than generating multiple ZIP's per agent group. Updated build timestamp format to match format used in old Ant script. Part of work for AME-2042.