JIRA: https://jira.spring.io/browse/INT-4013
Previously we couldn't define a config as :
````xml
<int:channel-interceptor pattern="input*">
<ref bean="sampleInterceptor" />
</int:channel-interceptor>
````
* Fix `GlobalChannelInterceptorParser` to distinguish `BeanDefinitionParserDelegate.REF_ELEMENT` child elements
and extract an appropriate `BeanReference`
* Modify `GlobalChannelInterceptorTests-context.xml` to prove the fix and meet JIRA requirements
2cb5a0704a