Put back default strings on dialogs

But make them work by calling _t in render rather than
getDefaultProps().

Also sort out some 'Warning!' strings

src/i18n/strings/en_EN.json

@@ -121,6 +121,7 @@
   "zh-sg":"Chinese (Singapore)",
   "zh-tw":"Chinese (Taiwan)",
   "zu":"Zulu",
+  "A registered account is required for this action": "A registered account is required for this action",
   "A text message has been sent to +%(msisdn)s. Please enter the verification code it contains": "A text message has been sent to +%(msisdn)s. Please enter the verification code it contains",
   "accept": "accept",
   "%(targetName)s accepted an invitation": "%(targetName)s accepted an invitation",
@@ -132,6 +133,7 @@
   "Admin": "Admin",
   "Advanced": "Advanced",
   "Algorithm": "Algorithm",
+  "Authentication": "Authentication",
   "all room members": "all room members",
   "all room members, from the point they are invited": "all room members, from the point they are invited",
   "all room members, from the point they joined": "all room members, from the point they joined",
@@ -149,6 +151,7 @@
   "A new password must be entered.": "A new password must be entered.",
   "%(senderName)s answered the call": "%(senderName)s answered the call",
   "anyone.": "anyone",
+  "An error has occurred.": "An error has occurred.",
   "Anyone who knows the room's link, apart from guests": "Anyone who knows the room's link, apart from guests",
   "Anyone who knows the room's link, including guests": "Anyone who knows the room's link, including guests",
   "Are you sure?": "Are you sure?",
@@ -371,6 +374,7 @@
   "Reason": "Reason",
   "Revoke Moderator": "Revoke Moderator",
   "Refer a friend to Riot": "Refer a friend to Riot",
+  "Registration required": "Registration required",
   "rejected": "rejected",
   "%(targetName)s rejected the invitation": "%(targetName)s rejected the invitation",
   "Reject invitation": "Reject invitation",
@@ -513,7 +517,7 @@
   "VoIP conference started": "VoIP conference started",
   "VoIP is unsupported": "VoIP is unsupported",
   "(warning: cannot be disabled again!)": "(warning: cannot be disabled again!)",
-  "Warning": "Warning",
+  "Warning!": "Warning!",
   "Who can access this room?": "Who can access this room?",
   "Who can read history?": "Who can read history?",
   "Who would you like to add to this room?": "Who would you like to add to this room?",