Fix incorrect XSD appinfo annotation, expected 'type' attribute value on the 'error-handler' attribute of the 'cq-listener-container' element.

In the Spring Data GemFire XML namespace defined by the XSD, the <gfe:cq-listener-container>, 'error-handler' attribute appinfo annotation expected 'type' is incorrectly defined as java.util.concurrent.Executor instead of org.springframework.util.ErrorHandler causing issues for IDEs (e.g. Eclipse) during auto-complete and pre-compilation type checking.

The appinfo annotation 'type' attribute value is currently incorrect the following Spring GemFire XSDs...

spring-gemfire-1.5.xsd
spring-gemfire-1.6.xsd
spring-gemfire-1.7.xsd