aaa: Expose only Directory name via DirectoryEntry

In many places of the code Directory is addresses as an entity.
Since it holds only the directory name as a field, DirectoryEntry is
changed to contain the DirectoryName.
This is a step in order to move Directory from common to aaa.

Topic: AAA
Change-Id: Ic5a1226902597d148e9cf57c9dc1f5be4d76d31e
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>