[HEAD MERGE] Add jul-app ABI/API and handle registration

Registration is done in the jul thread and the created jul-app are
attached to existing UST app.

Signed-off-by: David Goulet <dgoulet@efficios.com>
[MERGE] Enable a single JUL event working

Signed-off-by: David Goulet <dgoulet@efficios.com>
[MERGE] Enable all JUL event command

Signed-off-by: David Goulet <dgoulet@efficios.com>
[MERGE] disable a JUL event and all

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