Bug 1977: FSMongo Reverse Sync

Directories represented by a symlink are not stored properly on reverse
sync, resulting in empty directories being created instead of preserving
the link

Fixes Bug 1977

Change-Id: Ia6a3b3dfdfde498751a79e04b2824ac38d0b7feb
Signed-off-by: beierlm <mark.beierl@canonical.com>