Fix: Java agent protocol network endianness consistency

Considering the Agent Protocol is bumped to v2.0 as of 2.8.x,
this patch revisits the unfortunate decision of communicating
in host-endianness from the session daemon to the agents, and
in big endian from the agents to the session daemon.

This change does not affect the Python agent which was erroneously
(although quite reasonably) assuming communications were occurring
in network endianness.

This issue does not affect versions 2.7 and below because the loglevel
was not used.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>