Switch to Squid for our caching HTTP proxy needs.

Using Squid instead of Apache is faster and less resource intensive, and
gives us and our users oppourtunities to tune the cache for their
expected workload.
Make Docker nodes use IPv6 for their bringup.

Since they are not tied to IPv4 like Sledgehammer is for PXE, just let
them use native IPv6 from the start.
Kill chef_gem related timeouts.

This probably needs to be dropped as well.
Remove magic from our automatic IPv6 range.

Instead of relying on hardcoded magic to determine what the IPv6 address
for a node is, track it in the database along with the IPv4 ranges.
Add utility views for faster handling of framework roles.

These views encapsulate all the knowledge we need to deal with our DHCP,
Docker, and DNS records.
Refactor high-contnetion framework roles to use the specialized views.

This undoes the per-node logic I used to have in the Rails framework,
and since the database is doing all the heavy lifting it is just about
as fast.