Bug 10307 - z39.50 server search tab shows z390.50

The label on the global search form for Z39.50 administration reads
"Z390.50." This patch corrects the typo.

To test, apply the patch and navigate to Administration -> Z39.50
servers. The label on the global search tab should read "Search Z39.50
servers."

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