added option to remove ssh public keys from auth (ssh_auth.absent)

pillar.example

       pubkey: PUBLICKEY
     ssh_auth:
       - PUBLICKEY
+    ssh_auth.absent:
+      - PUBLICKEY_TO_BE_REMOVED
 
   ## Absent user
   cuser:

users/init.sls

 {% endfor %}
 {% endif %}
 
+{% if 'ssh_auth.absent' in user %}
+{% for auth in user['ssh_auth.absent'] %}
+ssh_auth_delete_{{ name }}_{{ loop.index0 }}:
+  ssh_auth.absent:
+    - user: {{ name }}
+    - name: {{ auth }}
+    - require:
+        - file: {{ name }}_user
+        - user: {{ name }}_user
+{% endfor %}
+{% endif %}
 
 {% if 'sudouser' in user and user['sudouser'] %}
 {% if not used_sudo %}