This reverts commit 4788875a.

See http://blog.springsource.org/2013/01/16/next-stop-spring-framework-4-0
for details.

The new jdiff task generates a report of API differences between the
current version (i.e. the value of `version` in gradle.properties) and
any older version of the framework, as specified by -DOLD_VERSION at
the command line, or defaulting to `previousVersion` in
gradle.properties.

Running the command requires a separate clone directory pinned to the
desired old version, as specified by -DOLD_VERSION_ROOT at the command
line. This creates challenges from a build automation perspective,
largely because Gradle doesn't (yet) have APIs for working with Git.

This task may be further automated and included in nightly CI runs, but
in the meantime, a number of reports back to 3.1.3.RELEASE have been
generated manually and uploaded to [1], where one can now find the
following entries in the directory listing:

 - 3.1.3.RELEASE_to_3.2.0.RC1
 - 3.2.0.M1_to_3.2.0.M2
 - 3.2.0.M2_to_3.2.0.RC1
 - 3.2.0.RC1_to_3.2.0.BUILD-SNAPSHOT

Ideally, the final entry there would be kept up-to-date on a daily
basis - again we may revisit doing so in the future. Going forward,
reports will be generated and uploaded manually on an as needed basis
and as part of the release process.

The goal of these reports are as follows:

 - to ease the process of ensuring backward compatibility

 - to aid in code reviews, particularly when reviewing large pull
   requests

 - to ease the process of creating migration guides for project
   maintainers, i.e. to help us remember what's changed

 - to allow ambitious end-users to discover what's been changing at the
   API level without without needing to wait for detailed "what's new in
   version X" and/or migration guide documentation

See documentation in jdiff.gradle for usage details.

Note that the jdiff-1.1.1 distribution as downloaded from [2] has been
added wholesale to the source tree under gradle/jdiff instead of
uploading JDiff jars to repo.springsource.org as we would normally do.
This is due to some unfortunate limitations in the implementation of the
jdiff ant task that require a phisical JDIFF_HOME directory. Checking in
the jars and various resources represents the simplest and most
pragmatic solution to this problem, though ambitious contributors are
free to do what's necessary to arrive at a more elegant arrangement.

[1]: http://static.springframework.org/spring-framework/docs
[2]: http://sourceforge.net/projects/javadiff/files/latest/download

Issue: SPR-9957

 - Use recent Gradle 1.0-milestone-8 snapshot
 - Add initial cut of build.gradle able to compile/test all modules
 - Update .gitignore
 - Generate Gradle wrapper scripts
 - Remove all Eclipse metadata files
 - Temporarily @Ignore tests that do not pass under Gradle