add travis.yml config for continuous integration builds on TravisCI

This will help with pull requests and developers that use AffdexMe as a starting point.

.travis.yml

@@ -0,0 +1,18 @@
+sudo: false
+language: android
+android:
+  components:
+    - tools
+    - build-tools-23.0.2
+    - android-23
+    - extra
+    - platform-tools
+
+script:
+  - wget http://affdex-sdk-dist.s3-website-us-east-1.amazonaws.com/android/download_sdk.html
+  # copy the SDK's assets into app/src/main/assets/
+  - unzip download_sdk.html "src/main/assets/*" -d app
+  # copy the SDK's libs into app/libs/
+  - unzip download_sdk.html "libs/*" -d app
+  - ./gradlew clean build test
+

README.md

@@ -1,3 +1,4 @@
+[![Build Status](https://travis-ci.org/Affectiva/affdexme-android.svg)](https://travis-ci.org/Affectiva/affdexme-android)
 ![Affectiva Logo](http://developer.affectiva.com/images/logo.png)
 
 ###Copyright (c) 2016 Affectiva Inc. <br> See the file [license.txt](license.txt) for copying permission.