nrpe should check jujud by default

[Felipe Reyes]

When monitoring via nrpe is added to a unit, by default it should always add a check for jujud of the unit where it's running on at least.

Here is an example for rabbitmq-server:

$ /usr/lib/nagios/plugins/check_procs -C jujud -a "--unit-name rabbitmq-server/0" -w 1:1 -c 1:1
PROCS OK: 1 process with command name 'jujud', args '--unit-name rabbitmq-server/0' | procs=1;1:1;1:1;0;