Default to XFS for rhel7/centos7

This is the default filesystem for both distros, and using ext4
creates some weird mismatches in things like fstab.  I've also hit
some ext4 resize bugs that this will eliminate, at the risk of
exposing new and different xfs bugs.
Export FS_TYPE in instack-virt-setup

I don't think it will be respected otherwise.
Cherry pick fix for tuskar-ui to tuskar-api race condition
Drop ancient discovery-related code

This code was in use when discoverd was a patch to Ironic and makes
no sense now. Stop putting discovery images in Glance, because
they're not consumed from Glance.
Delete not existent cinder params

Cinder params regarding Neutron has been deleted from
block-storage.yaml template. We should not set them,
otherwise Tuskar throws an error.
Merge branch 'master' of https://github.com/cybertron/instack-undercloud into cybertron-master

Conflicts:
	scripts/instack-build-images
Merge branch 'cybertron-master'
Merge pull request #91 from Ladas/fix_cinder_storage_params

Delete not existent cinder params
Use sudo when running os-apply-config so that we can always read the data files
Merge pull request #86 from rwsu/tuskar-race

Cherry pick fix for tuskar-ui to tuskar-api race condition
Remove merged cherry-picks and update commit hash of RDO specific patch
Add sysctl to all images

This is needed to customize the default kernel keepalive timings, see
https://bugzilla.redhat.com/show_bug.cgi?id=1167414
Merge pull request #94 from gfidente/sysctl

Add sysctl to all images
Switch to using upstream ironic-discoverd-ramdisk element

The element was backported from diskimage-builder master.
It mostly contains some clean ups.

We'll carry on the ramdisk development here, while trying to keep
the DIB version more or less up-to-date.
Merge pull request #92 from Divius/ironic-discoverd-1.0.0

Cleanups before switch to Kilo ironic-discoverd