LP#1398107: Add header to generic alerts.

LP#1398107: Add header to generic alerts.

Currently, generic alerts/events passed up from the Perl
layer are presented in an unadorned modal that just begins
with "Reason(s) include" without further context.  This
adds a "Could not Complete the Action" header with the
idea that something is better than nothing.  At this point,
i18n is not considered.

Signed-off-by: Chris Sharp <csharp@georgialibraries.org>
Signed-off-by: Rogan Hamby <rogan.hamby@gmail.com>
Signed-off-by: Jason Stephenson <jason@sigio.com>