CAS-1305 Restore jstl and standard taglib dependencies.

This fixes the following error on hitting /cas/login:

java.lang.NoClassDefFoundError: javax/servlet/jsp/jstl/core/Config
org.springframework.web.servlet.support.JstlUtils.exposeLocalizationContext(JstlUtils.java:97)
org.springframework.web.servlet.view.JstlView.exposeHelpers(JstlView.java:135)
org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:211)