Misc fixes to search and UI.

- Use prefContext to create preference.
- rename "Gestures" to "Gesture shortcuts"
- Add search keyword to individual gesture settings so when search
  "gesture" they also show up.
- call super() for all getNonIndexableKeys() in search provider

Fix: 38327387
Fix: 36621897
Fix: 36685646
Test: make RunSettingsRoboTests

Change-Id: Ia5ddfeae08cb27c278dfb8d2376594e21d8f283c

src/com/android/settings/EncryptionAndCredential.java

@@ -253,7 +253,7 @@ public class EncryptionAndCredential extends SettingsPreferenceFragment implemen
 
         @Override
         public List<String> getNonIndexableKeys(Context context) {
-            final List<String> keys = new ArrayList<String>();
+            final List<String> keys = super.getNonIndexableKeys(context);
 
             final UserManager um = UserManager.get(context);