Show who redacted an event on hover

This should fix #3931 although it's not obvious who actually performed the redaction.

Signed-off-by: Travis Ralston <travpc@gmail.com>

src/components/views/messages/UnknownBody.js

@@ -23,9 +23,14 @@ module.exports = React.createClass({
     displayName: 'UnknownBody',
 
     render: function() {
+        let tooltip = _t("Removed or unknown message type");
+        if (this.props.mxEvent.isRedacted()) {
+            tooltip = _t("Message removed by %(userId)s", {userId: this.props.mxEvent.getSender()});
+        }
+
         const text = this.props.mxEvent.getContent().body;
         return (
-            <span className="mx_UnknownBody" title={_t("Removed or unknown message type")}>
+            <span className="mx_UnknownBody" title={tooltip}>
                 {text}
             </span>
         );

src/i18n/strings/en_EN.json

@@ -827,6 +827,7 @@
     "Autocomplete Delay (ms):": "Autocomplete Delay (ms):",
     "This Home server does not support groups": "This Home server does not support groups",
     "Loading device info...": "Loading device info...",
+    "Message removed by %(userId)s": "Message removed by %(userId)s",
     "Groups": "Groups",
     "Create a new group": "Create a new group",
     "Create Group": "Create Group",

src/i18n/strings/en_US.json

@@ -838,6 +838,7 @@
     "Autocomplete Delay (ms):": "Autocomplete Delay (ms):",
     "This Home server does not support groups": "This Home server does not support groups",
     "Loading device info...": "Loading device info...",
+    "Message removed by %(userId)s": "Message removed by %(userId)s",
     "Groups": "Groups",
     "Create a new group": "Create a new group",
     "Create Group": "Create Group",