Add support for play.google.com app links

As requested in #154

F-Droid/AndroidManifest.xml

@@ -294,6 +294,19 @@
                 <data android:host="www.f-droid.org" />
                 <data android:pathPrefix="/app/" />
             </intent-filter>
+
+            <intent-filter>
+                <action android:name="android.intent.action.VIEW" />
+
+                <category android:name="android.intent.category.DEFAULT" />
+                <category android:name="android.intent.category.BROWSABLE" />
+
+                <data android:scheme="http" />
+                <data android:scheme="https" />
+                <data android:host="play.google.com" /> <!-- they don't do www. -->
+                <data android:path="/store/apps/details" />
+            </intent-filter>
+
         </activity>
         <activity
             android:label="@string/menu_preferences"

F-Droid/src/org/fdroid/fdroid/AppDetails.java

@@ -348,6 +348,7 @@ public class AppDetails extends ActionBarActivity implements ProgressListener, A
      * Various different intents could cause us to show this activity, such as:
      * <ul>
      *     <li>market://details?id=[app_id]</li>
+     *     <li>https://play.google.com/store/apps/details?id=[app_id]</li>
      *     <li>https://f-droid.org/app/[app_id]</li>
      *     <li>fdroid.app:[app_id]</li>
      * </ul>
@@ -362,8 +363,14 @@ public class AppDetails extends ActionBarActivity implements ProgressListener, A
         String appId = null;
         if (data != null) {
             if (data.isHierarchical()) {
-                if (data.getHost() != null && data.getHost().equals("details")) {
+                final String host = data.getHost();
+                if (host == null) {
+                    Log.e(TAG, "Null host found in app link!");
+                    return null;
+                }
+                if (host.equals("details") || host.equals("play.google.com")) {
                     // market://details?id=app.id
+                    // https://play.google.com/store/apps/details?id=app.id
                     appId = data.getQueryParameter("id");
                 } else {
                     // https://f-droid.org/app/app.id