Remove DisposableBeanMethodInterceptor

Previously, any @Configuration class was enhanced to namely implement
DisposableBean in order to remove static callbacks that were registered
for that class. This leads to problem if an ApplicationContext is created
and destroyed within the lifecycle on another ApplicationContext in the
same class loader.

It turns out that the destruction callback is no longer necessary as the
interceptors are now stateless: the VM is free to reclaim any of those if
necessary.

Issue: SPR-12445
Remove compiler warning
AnnotationAttributesReadingVisitor defensively handles meta-annotation retrieval failure

Issue: SPR-12493
Latest dependency updates (Joda-Time 2.6, H2 1.4.182, Jettison 1.3.7, xpp3 1.1.4c)
Check the user of a SockJS request

Issue: SPR-12497
Enrich CONNECTED frames with Principal

Issue: SPR-12479
Add private method to remove duplication
Add info on intercepting static resource requests

Issue: SPR-10655
Fix issue where FormHttpMessageConverter fails to write multipart data

FormHttpMessageConverter incorrectly determines that the media type
"multipart/form-data; charset=utf-8" is not multipart. This commit
allows the media type to contain a charset parameter.
Add protected YamlProcessor.getFlattenedMap method

Add a protected getFlattenedMap method to the YamlProcessor that
subclasses can use to flatten a source Map so that it has the same
entries as the Properties, but retains order.

Issue: SPR-12499