Define pidFilePath for offical RHEL packages

The init script in these packages _assumes_ that this variable is
defined. Without it, it fails to properly start the service.

Author: danielwhite

templates/mongod.conf.j2

@@ -10,6 +10,9 @@ net:
 
 processManagement:
   fork: {{ mongodb_processmanagement_fork | to_nice_json}}
+  {% if mongodb_pidfile_path is defined and mongodb_pidfile_path != '' -%}
+  pidFilePath: {{ mongodb_pidfile_path }}
+  {% endif %}
 
 {% if mongodb_replication_replset -%}
 replication:

templates/mongod_init.conf.j2

@@ -10,6 +10,9 @@ net:
 
 processManagement:
   fork: {{ mongodb_processmanagement_fork | to_nice_json }}
+  {% if mongodb_pidfile_path is defined and mongodb_pidfile_path != '' -%}
+  pidFilePath: {{ mongodb_pidfile_path }}
+  {% endif %}
 
 security:
   authorization: 'disabled'

vars/RedHat.yml

@@ -7,3 +7,5 @@ mongodb_repository:
 
 mongodb_repository_gpgkey:
   "3.2": "https://www.mongodb.org/static/pgp/server-3.2.asc"
+
+mongodb_pidfile_path: "{{ '/var/run/mongodb/mongod.pid' if ('mongodb-org' in mongodb_package) else '' }}"