The following style updates have been made in anticipation of
substantive changes in subsequent commits:

 - organize imports
 - correct whitespace errors (leading spaces in code, tabs in Javadoc)
 - wrap Javadoc at 90 chars; make imperative ("Return" vs. "Returns")
 - use conventional constructor argument wrapping

A serialVersionUID has also been added to RestClientException and its
ResourceAccessException subclass for consistency with the rest of that
same exception hierarchy.

Issue: SPR-7938

SPR-7591 introduced a java.nio.charset.Charset field within
HttpStatusCodeException. The former is non-serializable, thus by
extension the latter also became non-serializable.

Because the Charset field is only used for outputting the charset name
in HttpStatusCodeException#getResponseBodyAsString, it is reasonable to
store the value returned by Charset#name() instead of the actual Charset
object itself.

This commit refactors HttpStatusCodeException's responseCharset field to
be of type String instead of Charset and adds tests to prove that
HttpStatusCodeException objects are once again serializable as expected.

Issue: SPR-9273, SPR-7591

This renaming more intuitively expresses the relationship between
subprojects and the JAR artifacts they produce.

Tracking history across these renames is possible, but it requires
use of the --follow flag to `git log`, for example

    $ git log spring-aop/src/main/java/org/springframework/aop/Advisor.java

will show history up until the renaming event, where

    $ git log --follow spring-aop/src/main/java/org/springframework/aop/Advisor.java

will show history for all changes to the file, before and after the
renaming.

See http://chrisbeams.com/git-diff-across-renamed-directories

refactored HTTP support into top-level package "org.springframework.http"; revised RestTemplate facility in package "org.springframework.web.client"