Blurb:: use statistics for the active expansion within multifidelity refinement

Description:: When performing adaptive refinement in multifidelity UQ
methods, this option adapts based on the statistics for the active
model level/fidelity.  This approach avoids some computational overhead in some
cases by avoiding expansion roll-up.

<b> Default Behavior </b>

<b> Expected Output </b>

<b> Usage Tips </b>

<b> Additional Discussion </b>

Topics::

Examples::

Theory::
Faq::
See_Also::
