Spinner Double-Bounce now available

Spinner from: https://tobiasahlin.com/spinkit/

client/components/main/spinner_double_bounce.jade

@@ -0,0 +1,7 @@
+template(name="spinnerDoubleBounce")
+  .sk-spinner.sk-spinner-double-bounce(class=currentBoard.colorClass)
+    +spinnerDoubleBounceRaw
+
+template(name="spinnerDoubleBounceRaw")
+  .sk-double-bounce1
+  .sk-double-bounce2

client/components/main/spinner_double_bounce.styl

@@ -0,0 +1,44 @@
+@import 'nib'
+
+// From https://github.com/tobiasahlin/SpinKit
+.sk-spinner-double-bounce {
+  width: 40px;
+  height: 40px;
+
+  position: relative;
+  margin: 100px auto;
+}
+
+.sk-double-bounce1, .sk-double-bounce2 {
+  width: 100%;
+  height: 100%;
+  border-radius: 50%;
+  background-color: #333;
+  opacity: 0.6;
+  position: absolute;
+  top: 0;
+  left: 0;
+
+  -webkit-animation: sk-bounce 2.0s infinite ease-in-out;
+  animation: sk-bounce 2.0s infinite ease-in-out;
+}
+
+.sk-double-bounce2 {
+  -webkit-animation-delay: -1.0s;
+  animation-delay: -1.0s;
+}
+
+@-webkit-keyframes sk-bounce {
+  0%, 100% { -webkit-transform: scale(0.0) }
+  50% { -webkit-transform: scale(1.0) }
+}
+
+@keyframes sk-bounce {
+  0%, 100% {
+    transform: scale(0.0);
+    -webkit-transform: scale(0.0);
+  } 50% {
+    transform: scale(1.0);
+    -webkit-transform: scale(1.0);
+  }
+}

config/const.js

@@ -54,6 +54,7 @@ export const ALLOWED_WAIT_SPINNERS = [
   'Cube',
   'Cube-Grid',
   'Dot',
+  'Double-Bounce',
   'Rotateplane',
   'Scaleout',
   'Wave'