Implement exponential backoff for failed Me2Me authentication attempts

remoting/webapp/_locales/en/messages.json

 {
   "ACCESS_CODE": {
     "message": "Access code",
     "description": "Label for the access code entry box. This is where the client user enters the code that permits access to the host."
   },
   "ACCESS_CODE_TIMER": {
     "message": "This access code will expire in $timeout$",
     "description": "Text displayed when the access code is due to time out within 30 seconds.",
     "placeholders": {
       "timeout": {
@@ skipping 120 matching lines @@
     "description": "Error displayed if authentication fails. This can be caused by stale credentials, in which logging out of the web-app and retrying can fix the problem."
   },
   "ERROR_BAD_PLUGIN_VERSION": {
     "message": "Some components required for Chromoting are missing. Please make sure you have installed the latest version and try again.",
     "description": "Error displayed if the host or client plugin are missing or if they could not be loaded."
   },
   "ERROR_GENERIC": {
     "message": "An unknown error occurred. Please sign out of Chromoting and try again.",
     "description": "Generic error message, displayed if something went wrong, but we aren't able to determine what, or the cause is too technical to be of use to a typical user."
   },
+  "ERROR_HOST_IS_DISABLED": {
+    "message": "Connections to the remote computer are temporarily blocked because somebody was trying to connect to it with invalid PIN. Please try again later.",
+    "description": "Error that is shown on the client side when the host is blocking all connections due to failed authentication attempts."
+  },
   "ERROR_HOST_IS_OFFLINE": {
     "message": "The remote computer is not responding to connection requests. Please verify that it is online and try again.",
     "description": "Error that is shown on the client side when we don't get a response from the host."
   },
   "ERROR_INCOMPATIBLE_PROTOCOL": {
     "message": "An incompatible version of Chromoting was detected. Please make sure that you have the latest version of Chromium and Chromoting on both computers and try again.",
     "description": "Error that is shown on the client side when incompatible Chromoting versions are installed on host and client."
   },
   "ERROR_INVALID_ACCESS_CODE": {
     "message": "The access code is invalid. Please try again.",
@@ skipping 201 matching lines @@
   },
   "WARNING_NAT_DISABLED": {
     "message": "NOTE: Policy settings permit connections only between computers within your network.",
     "description": "Message displayed at the bottom of the host screen if local policy dictates that NAT traversal is disabled, meaning that connections outside the local network will not work."
   },
   "YES": {
     "message": "Yes",
     "description": "Label for general-purpose 'Yes' buttons."
   }
 }