Add JavaScript for mobile alerts

app/assets/javascripts/mobile/mobile_alert.js

+(function() {
+  Diaspora.Mobile.Alert = {
+    _flash: function(message, type) {
+      var html = "<div class='alert alert-" + type + " alert-dismissible fade in' role='alert'>" +
+                    "<button type='button' class='close' data-dismiss='alert' aria-label='" +
+                      Diaspora.I18n.t("header.close") +
+                    "'>" +
+                      "<span aria-hidden='true'><i class='entypo-cross'></i></span>" +
+                    "</button>" +
+                    message +
+                  "</div>";
+      $("#flash-messages").append(html);
+    },
+
+    success: function(message) { this._flash(message, "success"); },
+
+    error: function(message) { this._flash(message, "danger"); }
+  };
+})();

spec/javascripts/mobile/mobile_alert_spec.js

+describe("Diaspora.Mobile.Alert", function() {
+  describe("_flash", function() {
+    beforeEach(function() {
+      spec.content().html("<div id='flash-messages'></div>");
+    });
+
+    it("appends an alert to the #flash-messages div", function() {
+      Diaspora.Mobile.Alert._flash("Oh snap! You got an error!", "error-class");
+      expect($("#flash-messages .alert")).toHaveClass("alert-error-class");
+      expect($("#flash-messages .alert").text()).toBe("Oh snap! You got an error!");
+    });
+  });
+
+  describe("success", function() {
+    it("calls _flash", function() {
+      spyOn(Diaspora.Mobile.Alert, "_flash");
+      Diaspora.Mobile.Alert.success("Awesome!");
+      expect(Diaspora.Mobile.Alert._flash).toHaveBeenCalledWith("Awesome!", "success");
+    });
+  });
+
+  describe("error", function() {
+    it("calls _flash", function() {
+      spyOn(Diaspora.Mobile.Alert, "_flash");
+      Diaspora.Mobile.Alert.error("Oh noez!");
+      expect(Diaspora.Mobile.Alert._flash).toHaveBeenCalledWith("Oh noez!", "danger");
+    });
+  });
+});