Add repo title and build passing badge
Title added to the front page of our repo
Adds a nice little Travis build status on the front page showing the Travis build's status on the repo's `master` branch.
+[![Build Status](https://travis-ci.org/edx/edx-app-android.svg?branch=master)](https://travis-ci.org/edx/edx-app-android)
+
+# edX Android
+
This is the source code for the edX mobile Android app. It is changing rapidly
and its structure should not be relied upon. See http://code.edx.org for other
parts of the edX code base.
