Add support for attachment file names

Send, receive, and save attachment filenames. Use them as suggested
names when saving files.

// FREEBIE

js/libtextsecure.js

@@ -39049,6 +39049,9 @@ MessageSender.prototype = {
                 proto.id = id;
                 proto.contentType = attachment.contentType;
                 proto.digest = result.digest;
+                if (attachment.fileName) {
+                    proto.fileName = attachment.fileName;
+                }
                 return proto;
             });
         }.bind(this));

js/views/attachment_view.js

@@ -91,6 +91,10 @@
         }
     },
     suggestedName: function() {
+        if (this.model.fileName) {
+            return this.model.fileName;
+        }
+
         var suggestion = 'signal';
         if (this.timestamp) {
             suggestion += moment(this.timestamp).format('-YYYY-MM-DD-HHmmss');

js/views/file_input_view.js

@@ -223,12 +223,17 @@
         },
 
         readFile: function(file) {
-            var contentType = file.type;
             return new Promise(function(resolve, reject) {
                 var FR = new FileReader();
                 FR.onload = function(e) {
-                    resolve({data: e.target.result, contentType: contentType});
+                    resolve({
+                      data: e.target.result,
+                      contentType: file.type,
+                      fileName: file.name
+                    });
                 };
+                FR.onerror = reject;
+                FR.onabort = reject;
                 FR.readAsArrayBuffer(file);
             });
         },

libtextsecure/sendmessage.js

@@ -124,6 +124,9 @@ MessageSender.prototype = {
                 proto.id = id;
                 proto.contentType = attachment.contentType;
                 proto.digest = result.digest;
+                if (attachment.fileName) {
+                    proto.fileName = attachment.fileName;
+                }
                 return proto;
             });
         }.bind(this));

protos/IncomingPushMessageSignal.proto

@@ -123,6 +123,7 @@ message AttachmentPointer {
   optional uint32  size        = 4;
   optional bytes   thumbnail   = 5;
   optional bytes   digest      = 6;
+  optional string  fileName    = 7;
 }
 
 message GroupContext {