Disable screen rotation (it leaks advertisers)

Rotate the screen while advertising, and the advertiser leaks (when the Activity is recreated). From then on, the on/off switch is broken (you're still advertising even if you flip the switch off).  Advertising only stops if you kill the app.

So, disable screen rotation until we support this.

eddystone-uid/tools/txeddystone-uid/TxEddystone-UID/app/src/main/AndroidManifest.xml

@@ -13,7 +13,8 @@
       android:theme="@style/AppTheme">
     <activity
         android:name=".MainActivity"
-        android:label="@string/app_name">
+        android:label="@string/app_name"
+        android:screenOrientation="portrait">
       <intent-filter>
         <action android:name="android.intent.action.MAIN"/>