Add spring-build 2.5.2

spring-build was previously included via an svn:external. Adding
directly to the source tree under Git to avoid the need for a git
submodule.

In order to build from any earlier commit, it is recommended to
export spring-build or symlink an existing copy into the root
of the spring-framework project and then build normally.

    $ svn export https://src.springsource.org/svn/spring-build/tags/project-build-2.5.2 spring-build

.gitignore

@@ -1,7 +1,12 @@
+.springBeans
+.DS_Store
 target
 integration-repo
 ivy-cache
-spring-build
 jmx.log
-.springBeans
-.DS_Store
+jxl.log
+jmx.log
+org.springframework.jdbc/derby.log
+org.springframework.spring-parent/.classpath
+org.springframework.spring-parent/.project
+org.springframework.test/test-output/