Fix: add JUL filter to UST event on logger_name

This is to avoid having the JUL event copied in each sessions. See
ticket description for more details.

To achieve this, JUL filtering has been added to fix that bug.

Fixes #773

Signed-off-by: David Goulet <dgoulet@efficios.com>

Conflicts:
	src/bin/lttng-sessiond/cmd.c