Remove the standard.jar. It’s apparently of old JSTL 1.0 version when the TLD URIs were without the /jsp path. With JSTL 1.2 as available here you don’t need a standard.jar at all. Just the jstl-1.2.jar in /WEB-INF/lib is sufficient.
See also:
- How to install JSTL? The absolute uri: http://java.sun.com/jstl/core cannot be resolved
- Our JSTL wiki page