Document the new style instance group filters

Document the ServerGroupAffinityFilter and ServerGroupAntiAffinityFilter
filters.

Add a note about the deprecated GroupAffinityFilter and
GroupAntiAffinityFilter filters. Also indicate that those filters can't
work together.

Update some markup.

Add notes about the role of the scheduler during migration and
evacuation.

Change-Id: Ibc7989baa336eed698704ca2de38e04f027269b0
Closes-Bug: #1298980
Closes-Bug: #1299066
Merge "Document the new style instance group filters"
training-labs scripts cleanup

By request, I am posting a cosmetic changeset to clean up spelling,
formatting, whitespace, and comments (some visible by script users) in
training-labs. A few variables and function names have been changed
(decapitalization, consistency).

Scope: This changeset does not affect the workings of the code and
therefore does not fix bugs. Bug fixes go into separate patches.

Special notes:
* Scripts/Neutron/Neutron.sh still installs quantum, but the naming
  within said script is now consistent. That can only be temporary,
  a switch to a more recent release should happen soonish.

* I left the numbers for steps in some scripts (Glance.sh); maybe
  the manuals are meant to refer to these numbers!? Of course, they
  will change occasionally (this time, for instance, I changed them
  to match the actual order).

* Scripts that use non-standard functionality should use bash, not sh;
  shebangs fixed

* I didn't touch README.md, training-guides-cluster-scripts.tar: these,
  too, are for a separate changeset

Related-Bug: #1312764
Change-Id: I01005f96b03ef3fbeeaa0b9d9d0e804aaed7af83