Removing dependency on vtkPVServerManagerRendering.

vtkInitializationHelper was using vtkSMUtilities which is in
vtkPVServerManagerRendering. That added an unnecessary dependency on rendering
which caused failure in Catalyst builds withoout rendering. Moving the
ListAttachedMonitors() method from vtkSMUtilities to vtkInitializationHelper to
overcome this issue.

Change-Id: Ife732871fd70709f48c132ed13c0b6dc241baf0d
Adding new Catalyst edition (Essentials).

Adding a new edition for Catalyst, named Essentials, which will include some of
the common filters. To make it easier to create such editions, extending
catalyze.py to take in multiple input directories. Essentials edition extends
the "Base" edition to add vtkPVArrayCalculator (for now). We will add more of
the commonly used filters subsequently.

Change-Id: I6565f9aee7767f24e7c414bba932e62375d84218
Merge topic 'catalyst_essentials_edition' into next

5dea12b Adding new Catalyst edition (Essentials).
770a3d7 Removing dependency on vtkPVServerManagerRendering.