LP#1758360: handle DOB display logic in egPatronSummary correctly

LP#1758360: handle DOB display logic in egPatronSummary correctly

This patch ensures that the patron DOB will be displayed or
obscured correctly by the standalone egPatronSummary directive
in the same way that the patron app does.

To test
-------
[1] In the web staff client, do a patron search, select two patrons,
    then click the Merge Patrons button.
[2] Note that the patron DOB is not displayed in the modal.
[3] Apply the patch and repeat step #1.
[4] This time, the patron DOB will be displayed (if the
    circ.obscure_dob library setting is not enabled) or the
    the field label will be clickable (and clicking it will
    cause the DOB to be displayed).

Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>