Add toast to "Return to default"

This makes for a better experience in my opinion

Change-Id: I735d30426795c17a143dde893e532a3f259b0703
diff --git a/res/values/custom_strings.xml b/res/values/custom_strings.xml
index 3f2a38e..51d8d23 100644
--- a/res/values/custom_strings.xml
+++ b/res/values/custom_strings.xml
@@ -183,5 +183,6 @@
    <string name="lockscreen_wallpaper_title">Wallpaper</string>
    <string name="lockscreen_wallpaper_set_title">Set lock screen wallpaper</string>
    <string name="lockscreen_wallpaper_clear_title">Clear lock screen wallpaper</string>
+   <string name="reset_lockscreen_wallpaper">Set to default</string>
 
 </resources>
diff --git a/src/org/omnirom/omnigears/LockscreenSettings.java b/src/org/omnirom/omnigears/LockscreenSettings.java
index e1ee563..99d7f14 100644
--- a/src/org/omnirom/omnigears/LockscreenSettings.java
+++ b/src/org/omnirom/omnigears/LockscreenSettings.java
@@ -24,6 +24,7 @@
 import android.os.Bundle;
 import android.preference.Preference;
 import android.preference.PreferenceScreen;
+import android.widget.Toast;
 
 import com.android.settings.SettingsPreferenceFragment;
 
@@ -53,6 +54,8 @@
             return true;
         } else if (preference == mClearWallpaper) {
             clearKeyguardWallpaper();
+            Toast.makeText(getView().getContext(), getString(R.string.reset_lockscreen_wallpaper),
+            Toast.LENGTH_LONG).show();
             return true;
         }
         return super.onPreferenceTreeClick(preferenceScreen, preference);