Add Indexing and Search for ChooseLockGenericFragment

- clean some imports
- add key and title to security_settings_picker.xml
- add ChooseLockGenericFragment in SearchIndexableResources

Change-Id: I867a1e11905cc4059d6eccabeab04d55cc3d799e

src/com/android/settings/ChooseLockGeneric.java

@@ -23,8 +23,6 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.pm.UserInfo;
 import android.os.Bundle;
-import android.os.Process;
-import android.os.UserHandle;
 import android.os.UserManager;
 import android.preference.Preference;
 import android.preference.PreferenceScreen;