Since we already introduced apache server for redfish,
it will be a good idea to use it for sharing iso also.
These changes add file-exchanger config that can be
used to share iso. In addition apache allows the
specified users (see rbac config) to upload files.
This may help in future to better emulate deployment
environment, where it will be necessary to do this
step after airshipctl generated iso and before
airshipctl invokes redfish to run that iso.
Change-Id: Ice47fe977fb71cf9df14d39c5ac26e365e2006f2
16d2c8d8c1