Show keys with android contacts

This means to sync userid + keyid into contact storage. Android will merge them to normal contacts based on primary userid.

OpenKeychain/src/main/res/values/strings.xml

@@ -521,5 +521,6 @@
     <string name="error_no_encrypt_subkey">No encryption subkey available!</string>
     <string name="info_no_manual_account_creation">Do not create OpenKeychain-Accounts manually.
         For more information, see Help.</string>
+    <string name="contact_show_key">Show key (%s)</string>
 
 </resources>

OpenKeychain/src/main/res/xml/custom_pgp_contacts_structure.xml

@@ -1,7 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <ContactsSource xmlns:android="http://schemas.android.com/apk/res/android">
     <ContactsDataKind android:mimeType="vnd.android.cursor.item/vnd.org.sufficientlysecure.keychain.key"
-                      android:icon="@drawable/key_small"
-                      android:summaryColumn="data1"
-                      android:detailColumn="data2"/>
+                      android:detailColumn="data1"/>
 </ContactsSource>