Add support for more flexible container port exposing

Fixes #171 (Github Issue).

roles/matrix-corporal/tasks/validate_config.yml

@@ -2,7 +2,7 @@
 
 - name: Fail if required matrix-corporal settings not defined
   fail:
-    msg: >
+    msg: >-
       You need to define a required configuration setting (`{{ item }}`) for using matrix-corporal.
   when: "vars[item] == ''"
   with_items:
@@ -15,3 +15,13 @@
   fail:
     msg: "The Matrix Corporal HTTP API is enabled (`matrix_corporal_http_api_enabled`), but no auth token has been set in `matrix_corporal_http_api_auth_token`"
   when: "matrix_corporal_http_api_enabled|bool and matrix_corporal_http_api_auth_token == ''"
+
+
+- name: (Deprecation) Catch and report renamed corporal variables
+  fail:
+    msg: >-
+      Your configuration contains a variable, which now has a different name.
+      Please change your configuration to rename the variable (`{{ item.old }}` -> `{{ item.new }}`).
+  when: "item.old in vars"
+  with_items:
+    - {'old': 'matrix_corporal_container_expose_ports', 'new': '<superseded by matrix_corporal_container_http_gateway_host_bind_port and matrix_corporal_container_http_api_host_bind_port>'}