Added a receiver to listen to app uninstalls

OpenKeychain/src/main/AndroidManifest.xml

@@ -110,6 +110,13 @@
                 <action android:name="org.torproject.android.intent.action.STATUS"/>
             </intent-filter>
         </receiver>
+        <!-- broadcast receiver for listening to package uninstalls -->
+        <receiver android:name=".remote.PackageUninstallReceiver">
+            <intent-filter>
+                <action android:name="android.intent.action.PACKAGE_FULLY_REMOVED" />
+                <data android:scheme="package"/>
+            </intent-filter>
+        </receiver>
         <!-- singleTop for NFC dispatch, see SecurityTokenOperationActivity -->
         <activity
             android:name=".ui.MainActivity"

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/remote/PackageUninstallReceiver.java

@@ -0,0 +1,18 @@
+package org.sufficientlysecure.keychain.remote;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.net.Uri;
+
+import org.sufficientlysecure.keychain.provider.KeychainContract;
+
+public class PackageUninstallReceiver extends BroadcastReceiver {
+
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        String packageName = intent.getData().getEncodedSchemeSpecificPart();
+        Uri appUri = KeychainContract.ApiApps.buildByPackageNameUri(packageName);
+        context.getContentResolver().delete(appUri, null, null);
+    }
+}