remove retouching code from updater

Removes the retouch_binaries and undo_retouch_binaries from updater;
newly generated OTA packages should not call them any more.

Note that applypatch retains the ability to unretouch a file as it
reads it.  This will be needed as long as we want to support OTAs from
devices that were installed with retouching.

Change-Id: Ib3f6baeae90c84ba85983f626d821ab7e436ceb2