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

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

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2010 SpringSource
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+@IMPORT url("highlight.css");
+
+html {
+  padding:       0pt;
+  margin:        0pt;
+}
+
+body {
+  margin-left:   10%;
+  margin-right:  10%;
+  font-family:   Arial, Sans-serif;
+}
+
+div {
+  margin:        0pt;
+}
+
+p {
+  text-align:    justify;
+}
+
+hr {
+  border:        1px solid gray;
+  background:    gray;
+}
+
+h1,h2,h3,h4 {
+  color:         #234623;
+  font-family:   Arial, Sans-serif;
+}
+
+pre {
+  line-height:   1.0;
+  color:         black;
+}
+
+pre.programlisting {
+  font-size:     10pt;
+  padding:       7pt 3pt;
+  border:        1pt solid black;
+  background:    #eeeeee;
+  clear:         both;
+}
+
+div.table {
+  margin:        1em;
+  padding:       0.5em;
+  text-align:    center;
+}
+
+div.table table {
+  display:       table;
+  width:         100%;
+}
+
+div.table td {
+  padding-left:  7px;
+  padding-right: 7px;
+}