container: add default support for IPv6 (#4448)

* Initial update

* update docs and test files

tests/unit/settings/user_settings.yml

@@ -12,7 +12,7 @@ search:
 
 server:
   port: 9000
-  bind_address: "0.0.0.0"
+  bind_address: "[::]"
   secret_key: "user_settings_secret"
   base_url: false
   image_proxy: false

tests/unit/settings/user_settings_keep_only.yml

@@ -5,7 +5,7 @@ use_default_settings:
       - wikinews
 server:
   secret_key: "user_secret_key"
-  bind_address: "0.0.0.0"
+  bind_address: "[::]"
   default_http_headers:
     Custom-Header: Custom-Value
 engines:

tests/unit/settings/user_settings_remove.yml

@@ -5,6 +5,6 @@ use_default_settings:
       - wikinews
 server:
   secret_key: "user_secret_key"
-  bind_address: "0.0.0.0"
+  bind_address: "[::]"
   default_http_headers:
     Custom-Header: Custom-Value

tests/unit/settings/user_settings_remove2.yml

@@ -5,7 +5,7 @@ use_default_settings:
       - wikinews
 server:
   secret_key: "user_secret_key"
-  bind_address: "0.0.0.0"
+  bind_address: "[::]"
   default_http_headers:
     Custom-Header: Custom-Value
 engines:

tests/unit/settings/user_settings_simple.yml

@@ -1,7 +1,7 @@
 use_default_settings: true
 server:
   secret_key: "user_secret_key"
-  bind_address: "0.0.0.0"
+  bind_address: "[::]"
   default_http_headers:
     Custom-Header: Custom-Value
 result_proxy: