Gallery2: Hide "Settings" item from menu. (GallerySettings are empty)

Patch Set 2: minor typo fix
Patch Set 3: Peter Gregus's easier solution

  * inspired from Geo-Piskas's cm-10.1 patches
  * https://github.com/CyanogenMod/android_packages_apps_Gallery2/commit/dde77bda2f1f1923026d7164b38298821f1c825b
  * https://github.com/CyanogenMod/android_packages_apps_Gallery2/commit/3afe270b445e8804d894166652672c0947d915f1
  * Thanks to Peter Gregus for easier solution

As soon as GallerySettings.java has content, settings should be set
to visible in albumset.xml.
Menu without "Settings": http://i.imgur.com/gOX7x.png

Change-Id: I499abad5bcc42d19724026c943b0a2b14f2f8bab