CMFileManager: Fixes for non-rooted devices

Various fixes for non-rooted devices running under java console:

 * Improve navigation (caching unsused data on chrooted mode: aids, mountpoints, ...)
 * Editor: Don't ask user to gain privileges (non rooted devices never can gain privileged access)
 * Move common file operations to FileHelper
 * MoveCommand: As shell console, java console doesn't allow to move between filesystems. Use
   a copy-delete operation when renameTo is not allowed.
 * On non-rooted devices, not allow to change to other access mode.

Change-Id: I7ae8b4f4203fc8a20f498e43f45c0a956731b02e