Thread model and UI improvements

Adds thread model/collection for managing conversation-level state, such
as unreadCounts, group membership, thread order, etc... plus various UI
improvements enabled by thread model, including an improved compose
flow, and thread-destroy button.

Adds Whisper.notify for presenting messages to the user in an orderly
fashion. Currently using a growl-style fade in/out effect.

Also some housekeeping:
Cut up views into separate files.
Partial fix for formatTimestamp.
Tweaked buttons and other styles.

js/models/threads.js

@@ -0,0 +1,94 @@
+var Whisper = Whisper || {};
+
+(function () {
+  'use strict';
+
+  var Thread = Backbone.Model.extend({
+    defaults: function() {
+      return {
+        image: '/images/default.png',
+        unreadCount: 0,
+        timestamp: new Date().getTime()
+      };
+    },
+
+    validate: function(attributes, options) {
+      var required = ['id', 'type', 'recipients', 'timestamp', 'image', 'name'];
+      var missing = _.filter(required, function(attr) { return !attributes[attr]; });
+      if (missing.length) { return "Thread must have " + missing; }
+      if (attributes.recipients.length === 0) {
+        return "No recipients for thread " + this.id;
+      }
+      for (var person in attributes.recipients) {
+        if (!person) return "Invalid recipient";
+      }
+    },
+
+    sendMessage: function(message) {
+      return new Promise(function(resolve) {
+        var m = Whisper.Messages.addOutgoingMessage(message, this);
+        textsecure.sendMessage(this.get('recipients'), m.toProto(),
+          function(result) {
+            console.log(result);
+            resolve();
+          }
+        );
+      }.bind(this));
+    },
+
+    messages: function() {
+      return Whisper.Messages.where({threadId: this.id});
+    },
+  });
+
+  Whisper.Threads = new (Backbone.Collection.extend({
+    localStorage: new Backbone.LocalStorage("Threads"),
+    model: Thread,
+    comparator: 'timestamp',
+    findOrCreate: function(attributes) {
+      var thread = Whisper.Threads.add(attributes, {merge: true});
+      thread.save();
+      return thread;
+    },
+
+    findOrCreateForRecipients: function(recipients) {
+      var attributes = {};
+      if (recipients.length > 1) {
+        attributes = {
+          //TODO group id formatting?
+          name       : recipients,
+          recipients : recipients,
+          type       : 'group',
+        };
+      } else {
+        attributes = {
+          id         : recipients[0],
+          name       : recipients[0],
+          recipients : recipients,
+          type       : 'private',
+        };
+      }
+      return this.findOrCreate(attributes);
+    },
+
+    findOrCreateForIncomingMessage: function(decrypted) {
+      var attributes = {};
+      if (decrypted.message.group) {
+        attributes = {
+          id         : decrypted.message.group.id,
+          name       : decrypted.message.group.name,
+          recipients : decrypted.message.group.members,
+          type       : 'group',
+        };
+      } else {
+        attributes = {
+          id         : decrypted.pushMessage.source,
+          name       : decrypted.pushMessage.source,
+          recipients : [decrypted.pushMessage.source],
+          type       : 'private'
+        };
+      }
+      return this.findOrCreate(attributes);
+    }
+  }))();
+})();