Add spring-build 2.2.3.

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-2.2.3 spring-build

spring-build/docbook/css/html/highlight.css

@@ -0,0 +1,35 @@
+/* 
+   code highlight CSS resemblign the Eclipse IDE default color schema
+   @author Costin Leau
+*/
+
+.hl-keyword {
+  color: #7F0055;
+  font-weight: bold; 
+}
+
+.hl-comment {
+  color: #3F5F5F;
+  font-style: italic;
+}
+
+.hl-multiline-comment {
+  color: #3F5FBF;
+  font-style: italic;
+}
+
+.hl-tag {
+  color: #3F7F7F;
+}
+
+.hl-attribute {
+  color: #7F007F;
+}
+
+.hl-value {
+  color: #2A00FF;
+}
+
+.hl-string {
+  color: #2A00FF;
+}