Add import to projects jspf

Author: ahornace

opengrok-web/src/main/webapp/projects.jspf

@@ -26,6 +26,7 @@ Portions Copyright (c) 2018, Chris Fraire <[email protected]>.
 --%>
 <%@page import="
 java.net.URLEncoder,
+java.nio.charset.StandardCharsets,
 org.opengrok.web.PageConfig
 "%><%
 /* ---------------------- projects.jspf start --------------------- */