Update ResourceHandlerReg. API for Resource handling

This change adds new methods in the ResourceHandlerRegistration API
for registering ResourceResolvers and ResourceTransformers, allowing
to better handle server-side resources in web applications.i

Here is an example of configuration for an HTML5 web application
that uses JavaScript and HTML5 appcache manifests:

    registry.addResourceHandler("/**")
      .addResourceLocations("classpath:static/")
      .addTransformer(new AppCacheManifestTransfomer())
      .addVersion("v1", "/**/*.js")
      .addVersionHash("/**");

Issue: SPR-11982
Add documentation for Java SockJS client

Issue: SPR-12006
Add to SockJsClient reference documentation

Issue: SPR-12006
Support HTTP HEAD method in MockMvcRequestBuilders

Surprisingly until now the MockMvcRequestBuilders did not have methods
for HTTP HEAD. This change adds such methods to the  API making it
consistent with other HTTP method types.

Issue: SPR-12055
Fix white spaces
Polish Javadoc for AnnotationCacheKey
Polish Javadoc for MutablePropertySources
Remove unused imports