[1/2] base: added config for menu unlock

Allow to define if menu unlock is enabled or not

Change-Id: Ibe498f5b6fc956678f426c9fdc9db28a0c483429

Patchset: 1
https://gerrit.omnirom.org/#/c/3317/

Already in cm source - core/java/android/provider/Settings.java

/**
  * Whether to unlock the menu key.  The value is boolean (1 or 0).
  * @hide
  */
 public static final String MENU_UNLOCK_SCREEN = "menu_unlock_screen";