ogisticRegression::save to serialize and store an LogisticRegression to disk.
 Load the LogisticRegression from this file again, by calling this function with the path to the file.
 Optionally specify the node for the file containing the classifier</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>filepath</code> - path to serialized LogisticRegression</dd>
<dd><code>nodeName</code> - name of node containing the classifier</dd>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>a