wily: collect_rabbitmq_stats.sh can't create lockfile

When nrpe is used with rabbitmq-server on Wily, the cron job which collects stats fails because the lockfile-create command isn't available (lockfile-progs package not installed in Wily deployments).

$ lockfile-create -r2 --lock-name /var/lock/rabbitmq-gather-metrics.lock
The program 'lockfile-create' is currently not installed. You can install it by typing:
sudo apt-get install lockfile-progs

...

This should fix it, validating...

=== modified file 'hooks/rabbit_utils.py'
--- hooks/rabbit_utils.py 2015-10-19 17:40:42 +0000
+++ hooks/rabbit_utils.py 2015-10-21 16:09:18 +0000
@@ -48,7 +48,7 @@

 from collections import OrderedDict

-PACKAGES = ['rabbitmq-server', 'python-amqplib']
+PACKAGES = ['rabbitmq-server', 'python-amqplib', 'lockfile-progs']

 RABBITMQ_CTL = '/usr/sbin/rabbitmqctl'
 COOKIE_PATH = '/var/lib/rabbitmq/.erlang.cookie'

=== modified file 'scripts/collect_rabbitmq_stats.sh'
--- scripts/collect_rabbitmq_stats.sh 2015-08-27 01:44:56 +0000
+++ scripts/collect_rabbitmq_stats.sh 2015-10-21 16:08:18 +0000
@@ -8,6 +8,7 @@
 # Check for a lock file and if not, create one
 lockfile-create -r2 --lock-name $LOCK > /dev/null 2>&1
 if [ $? -ne 0 ]; then
+ echo "Failed to create lockfile: $LOCK."
     exit 1
 fi
 trap "rm -f $LOCK > /dev/null 2>&1" exit