Publish Vulpes Preview 15 sources for desktop, Android and Tundra

Share Gaia assets and adapters, keep private profiles and development documents local, and update both public READMEs.

gaia/apps/system/style/browser_frame/private_browser.css

@@ -0,0 +1,30 @@
+* {
+  -moz-user-select: none;
+}
+
+html {
+  font-size: 10px;
+  width: 100%;
+  height: 100%;
+  padding: 0;
+}
+
+body {
+  width: 100%;
+  height: 100%;
+  margin: 0;
+  padding: 20.6rem 3rem 0;
+  -moz-box-sizing: border-box;
+  background: #392E54 url(images/pb_dialog.png) no-repeat center 5rem / 10.2rem 11.6rem;
+}
+
+h1 {
+    font-size: 2rem;
+}
+
+a, p {
+  color: #fff;
+  font-size: 1.3rem;
+  line-height: 1.8rem;
+  margin-bottom: 1rem;
+}