Fix: Add versioning to liblttng-ust-agent JAR

The liblttng-ust-agent JAR need versioning. The manifest file contains the
appropriate information about the JAR, such as the current version.

A symlink is also created and installed in order to point to the latest
version of the JAR.

e.g: liblttng-ust-agent.jar -> liblttng-ust-agent-1.0.0.jar

Signed-off-by: Christian Babeux <christian.babeux@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>