Update jobs to use the identifier scheme described in documentation

Job identifiers currently ignore both `identifier` and `name`.  If you
have two jobs defined that have the same `command`, the formula
currently blows up.

linux/system/job.sls

 - linux.system.cron
 
   {%- for name, job in system.job.items() %}
-    {%- set job_user = job.get('user', 'root') %}
+  {%- set job_user = job.get('user', 'root') %}
+  {%- set job_state_name = job.get('identifier', job.command) %}
 
-linux_job_{{ job.command }}:
+linux_job_{{ name }}:
     {%- if job.get('enabled', True) %}
   cron.present:
     - name: >
-        {{ job.command }}
+        {{ job_state_name }}
       {%- if job.get('identifier', True) %}
     - identifier: {{ job.get('identifier', job.get('name', name)) }}
       {%- endif %}
       {%- endif %}
     {%- else %}
   cron.absent:
-    - name: {{ job.command }}
+    - name: >
+        {{ job_state_name }}
       {%- if job.get('identifier', True) %}
     - identifier: {{ job.get('identifier', job.get('name', name)) }}
       {%- endif %}