LP#1472787: fix expansion of wildcard eg-grid-field paths

LP#1472787: fix expansion of wildcard eg-grid-field paths

This fixes a bug where expansion of wildcard egGridField
paths didn't handle a plain "*" correctly.

To test:

[1] In the web staff client, bring up the list of a patron's
    current loans.  Add the grace period column to the grid,
    but note that the loans' grace period values are not
    actually displayed.
[2] Apply the patch.
[3] Refresh the browser and repeat step 1.  This time, the
    grace period values are displayed.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>