Refactor common/utils methods to common/ondisk

Place all the methods related to on-disk layout and / or configuration
into a new common module that can be shared by the various modules
using the same on-disk layout.

Change-Id: I27ffd4665d5115ffdde649c48a4d18e12017e6a9
Signed-off-by: Peter Portante <peter.portante@redhat.com>
Merge "Refactor common/utils methods to common/ondisk"