android: Add settings activity and default profile selection

The default profile can then be used for a Quick Settings tile or the
Always-on VPN feature.

src/frontends/android/app/src/main/AndroidManifest.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!--
-    Copyright (C) 2012-2015 Tobias Brunner
+    Copyright (C) 2012-2018 Tobias Brunner
     Copyright (C) 2012 Giuliano Grassi
     Copyright (C) 2012 Ralf Sager
     HSR Hochschule fuer Technik Rapperswil
@@ -66,6 +66,10 @@
         <activity
             android:name=".ui.LogActivity"
             android:label="@string/log_title" >
+        </activity>
+		<activity
+            android:name=".ui.SettingsActivity"
+            android:label="@string/pref_title">
         </activity>
         <activity
             android:name=".ui.RemediationInstructionsActivity"