Store validations in Swift

(Converting from bug https://bugs.launchpad.net/tripleo/+bug/1625545)

This has been suggested as a followup to the initial validation implementation. Instead of having the validations called from a known disk location like we do now, we would keep them in Swift (similar to the way TripleO Heat templates are used).

Here's a few reasons:

1. The UI can't access the disk but it can talk to Swift so if we want to manipulate the validations (e.g. adding new ones, showing their contents, etc.) it's easier this way

2. At some point we want to have a highly available undercloud and at that point, we don't want the disks to be the primary locations of data, because we'd have to sync everything and it would lead to problems. Having Swift be the single source of truth lets us avoid this.

3. We can have additional tools that read/process the data without having to be running on the undercloud

These are basically the same reasons that led to Swift being the primary storage for THT and this just follows suit.