Also toggle eligibility output based on value

Unset drain when final batch allocs finish

docs: clarify service.port depends on address_mode

add HasHealth helper for nil checks

This PR handles upgrading a node that has no scheduling eligiblity set.

handle missing finishedAt

UI: Service job breadcrumbs + errant open connections

It was possible for a url to be overridden then canceled, leaving the
open connection open and forgotten about.

Add node events to documentation

Filter desired status stop allocs correctly 

drain: block cli until all allocs stop

This PR allows aliased commands to be autocompleted but still filters
them from the help output.

UI: Upgrade Ember to LTS + fix job summary issues

UI: Check for a case-sensitive or lowercase header value

Before the drain CLI would block until the node was marked as completing
drain operations. While technically correct, it could lead operators (or
more likely: scripts) to shutdown drained nodes before all of its
allocations had *actually* terminated.

This change makes the CLI block until all allocations have terminated
(unless ignoring system jobs).

This reverts commit 74fc5543.

We performed the DeploymentStatus nil checks a couple different ways, so
hopefully this helper will consoldiate them and make it more clear what
the code is doing.