Issue: SPR-8843

Issue: SPR-8842

The Content-Type header and the contentType field in HttpServletRequest/Response
are now always in sync. When a header is added the contentType field is updated
as well and vice versa. 

Similarly when the Content-Type header or the contentType field includes a charset 
field, the character encoding is updated and vice versa.

Issue: SPR-8852

Separate concerns of @Configuration class selection from the need to
register certain infrastructure beans such as auto proxy creators.

Prior to this change, ImportSelector implementations were responsible
for both of these concerns, leading to awkwardness and duplication.

Also introduced in this change is ImportBeanDefinitionRegistrar and
two implementations, AutoProxyRegistrar and AspectJAutoProxyRegistrar.
See the refactored implementations of CachingConfigurationSelector,
TransactionManagementConfigurationSelector to see the former;
AspectJAutoProxyConfigurationSelector to see the latter.

ImportSelector and ImportBeanDefinitionRegistrar are both handled as
special-case arguments to the @Import annotation within
ConfigurationClassParser.

These refactorings are important because they ensure that Spring users
will be able to understand and extend existing @Enable* annotations
and their backing ImportSelector and @Configuration classes, as well
as create their own with a minimum of effort.

See EnableCaching Javadoc for details.

Issue: SPR-8312

Also eliminate all 'cache definition' language in favor of
'cache operation' in comments, method and parameter names (most
classes had already been refactored to this effect).

Unfortunately creates a large diff due to whitespace changes as well as
false attribution of authorship from a git/svn 'blame' perspective.

Be sure to perform diffs using `git diff -w` or `svn diff -w` when
reviewing recent changes to these sources to ignore all whitespace.

In favor of existing #setCacheOperationSources(CacheOperationSource...)

Also polish Javadoc throughout, replacing stale references to
CacheDefinitionSource where appropriate as well as other minor changes

Facilitates type-safe programmatic configuration from @Bean methods:

    @Bean
    public CacheManager cacheManager() {
        SimpleCacheManager cm = new SimpleCacheManager();
        cm.setCaches(Arrays.asList(
            new ConcurrentMapCache("default"),
            new ConcurrentMapCache("primary"),
            new ConcurrentMapCache("secondary")
        ));
        return cm;
    }

Prior to this change, the code above would have raised errors on the
Arrays.asList() call because it returns a Collection<? extends Cache>
as opposed to Collection<Cache>.

After this change, AbstractCacheManager expects
Collection<? extends Cache> throughout.

This was removed once previously but accidentally re-introduced later.
The 'correct' version of spring-cache-3.1.xsd lives in spring-context
as opposed to here in spring-context-support.

Also placed .gitignore file within src/main/resources such that the
now-empty directory does not get pruned in git environments, which will
otherwise cause 'missing source folder' errors within Eclipse/IDEA.

Refactored getConfig => getApplicationContext such that subclasses have
control over the type of ApplicationContext used by the base class
tests. Done in anticipation of @EnableCaching tests that will favor use
of AnnotationConfigApplicationContext

Also updated all use of ClassPathXmlApplictionContext to
GenericXmlApplicationContext, which is generally preferred.

There was some question about whether enabling subclass proxies via
proxyTargetClass / proxy-target-class settings would break annotation-
based demarcation of joinpoints due to inability to discover those
annotations in various scenarios. The provided tests prove that in
any conceivable case, these annotations (@Transactional, at least)
are discovered in a consistent fashion, meaning that switching proxy
strategies should be transparent to the application and honor
intended annotation semantics.

Minor improvements made during the triage of SPR-8817

Issue: SPR-8838

Add reference to @EnableScheduling and <task:annotation-driven>

If no values are given, the query parameter is removed.

SPR-8082
SPR-7833
+ add support for CacheDefinitions declarations inside XML
+ more integration tests

+ introduced @CacheDefinition annotation
+ introduced meta-annotation to allow multiple @cache annotations
SPR-7833
SPR-8082