Container list block does not consider children of unittitle

[ctgraham]

The Container List block draws the text() directly from unittitle:

islandora_solution_pack_manuscript/includes/jstreebuilder.inc

Lines 87 to 88 in c0fee29

	$title = $this->xpath->evaluate('normalize-space(string(ead:did/ead:unittitle/text()))', $element);
	$date = $this->xpath->evaluate('normalize-space(string(ead:did/ead:unitdate/text()))', $element);

but, unittitle may contain all text in its children. E.g.:

<did>
  <unittitle>
    <title render="italic">My Publication Name</title>
  </unittitle>
  <unitid>12.</unitid>
</did>

A quick fix is to pull text nodes from descendant-or-self.