another minor pref tweak for mms fallback

1) fix summary for outgoing sms/mms
2) disable mms option when TS-users is unselected, same as the fallback
   approval option.

// FREEBIE

res/values/strings.xml

@@ -698,7 +698,8 @@
     <string name="preferences__sms_fallback">Outgoing SMS/MMS</string>
     <string name="preferences__submit_debug_log">Submit debug log</string>
     <string name="preferences__sms_outgoing_push_users">TextSecure users</string>
-    <string name="preferences__sms_fallback_push_users_ask">(ask first)</string>
+    <string name="preferences__sms_fallback_push_users_ask">ask first</string>
+    <string name="preferences__sms_fallback_push_users_no_mms">no MMS</string>
     <string name="preferences__sms_outgoing_push_users_description">Send secure SMS if data connectivity is lost</string>
     <string name="preferences__sms_fallback_ask_before_sending_sms_mms">Ask before sending SMS/MMS</string>
     <string name="preferences__sms_fallback_never_send_mms">Never send MMS</string>

src/org/thoughtcrime/securesms/components/OutgoingSmsPreference.java

@@ -38,11 +38,16 @@ public class OutgoingSmsPreference extends DialogPreference {
     dataUsers.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View v) {
-        askForFallback.setEnabled(dataUsers.isChecked());
+        updateEnabledViews();
       }
     });
 
+    updateEnabledViews();
+  }
+
+  private void updateEnabledViews() {
     askForFallback.setEnabled(dataUsers.isChecked());
+    neverFallbackMms.setEnabled(dataUsers.isChecked());
   }
 
   @Override

src/org/thoughtcrime/securesms/preferences/SmsMmsPreferenceFragment.java

@@ -12,6 +12,7 @@ import android.support.v4.app.Fragment;
 import android.support.v4.app.FragmentManager;
 import android.support.v4.app.FragmentTransaction;
 import android.support.v4.preference.PreferenceFragment;
+import android.text.TextUtils;
 
 import org.thoughtcrime.securesms.ApplicationPreferencesActivity;
 import org.thoughtcrime.securesms.MmsPreferencesFragment;
@@ -20,6 +21,9 @@ import org.thoughtcrime.securesms.components.OutgoingSmsPreference;
 import org.thoughtcrime.securesms.util.TextSecurePreferences;
 import org.thoughtcrime.securesms.util.Util;
 
+import java.util.LinkedList;
+import java.util.List;
+
 public class SmsMmsPreferenceFragment extends PreferenceFragment {
   private static final String KITKAT_DEFAULT_PREF = "pref_set_default";
   private static final String OUTGOING_SMS_PREF   = "pref_outgoing_sms";
@@ -92,11 +96,21 @@ public class SmsMmsPreferenceFragment extends PreferenceFragment {
     final StringBuilder builder         = new StringBuilder();
     final boolean       dataFallback    = TextSecurePreferences.isFallbackSmsAllowed(getActivity());
     final boolean       dataFallbackAsk = TextSecurePreferences.isFallbackSmsAskRequired(getActivity());
+    final boolean       mmsFallback     = TextSecurePreferences.isFallbackMmsEnabled(getActivity());
     final boolean       nonData         = TextSecurePreferences.isDirectSmsAllowed(getActivity());
 
     if (dataFallback) {
       builder.append(getString(R.string.preferences__sms_outgoing_push_users));
-      if (dataFallbackAsk) builder.append(" ").append(getString(R.string.preferences__sms_fallback_push_users_ask));
+
+      List<String> fallbackOptions = new LinkedList<>();
+      if (dataFallbackAsk) fallbackOptions.add(getString(R.string.preferences__sms_fallback_push_users_ask));
+      if (!mmsFallback)    fallbackOptions.add(getString(R.string.preferences__sms_fallback_push_users_no_mms));
+
+      if (fallbackOptions.size() > 0) {
+        builder.append(" (")
+               .append(TextUtils.join(", ", fallbackOptions))
+               .append(")");
+      }
     }
     if (nonData) {
       if (dataFallback) builder.append(", ");