ad-auth: make samba admin password location variable

ad-auth/defaults/main.yml

 ---
 
 ad_admin_group: admin
+ad_admin_password: samba-admin

ad-auth/tasks/sssd.yml

@@ -28,7 +28,7 @@
     - name: discover our realm
       command: realm discover -v "{{ domain }}"
     - name: get a kerberos ticket
-      shell: echo "{{ lookup('passwordstore', 'samba-admin') }}" | kinit Administrator
+      shell: echo "{{ lookup('passwordstore', ad_admin_password) }}" | kinit Administrator
       when: debian_version == "jessie"
       no_log: True
     - name: ensure pexpect is installed
@@ -38,7 +38,7 @@
       expect:
         command: kinit Administrator
         responses:
-          "Password for Administrator.*": "{{ lookup('passwordstore', 'samba-admin') }}"
+          "Passwor(d|t) for Administrator.*": "{{ lookup('passwordstore', ad_admin_password) }}"
       when: debian_version == "stretch"
       no_log: True
     - name: leave any other realm