Add the Spring IO plugin and align with the Platform where possible

Configure the Spring IO plugin such that it's only applied when the
build is run with -PplatformVersion=<version>. This platformVersion
property is used to determine the version of the Platform that will
be used when running the springIoCheck task. The plugin can be used
by running a build as follows:

./gradlew clean springIoCheck -PplatformVersion=1.0.1.RELEASE -PJDK7_HOME=… -PJDK8_HOME=…

This will test the project on JDK7 and JDK 8 using the dependencies
defined in Spring IO Platform 1.0.1.RELEASE.

Running the plugin identified a dependency on CGLib (use of
spring-core's repackaged CGLib is preferred), but the dependency
appears to be unused. It has been removed.

The versions of a number of other dependencies have been updated to
use their latest versions and align them with Spring IO Platform. Most
notable is probably a move from Guava 15.0 to 17.0.

build.gradle

@@ -4,6 +4,7 @@ buildscript {
     }
     dependencies {
         classpath 'org.springframework.build.gradle:docbook-reference-plugin:0.1.5'
+        classpath 'org.springframework.build.gradle:spring-io-plugin:0.0.3.RELEASE'
     }
 }
 
@@ -23,15 +24,26 @@ apply from: "$rootDir/maven.gradle"
 apply plugin: 'docbook-reference'
 apply plugin: 'application'
 
+if (project.hasProperty('platformVersion')) {
+    apply plugin: 'spring-io'
+
+    repositories {
+        maven { url "https://repo.spring.io/libs-snapshot" }
+    }
+
+    dependencies {
+        springIoVersions "io.spring.platform:platform-versions:${platformVersion}@properties"
+    }
+}
+
 [compileJava, compileTestJava]*.options*.compilerArgs = ["-Xlint:-serial", "-Xlint:unchecked", "-Xlint:rawtypes"]
 
 dependencies {
     compile "org.springframework:spring-core:$springVersion"
     compile "org.springframework:spring-context-support:$springVersion"
     compile "commons-io:commons-io:$commonsioVersion"
-    compile "com.google.guava:guava:15.0"
+    compile "com.google.guava:guava:$guavaVersion"
     compile "jline:jline:$jlineVersion"
-    compile "cglib:cglib:$cglibVersion"
 
     
     // Testing

gradle.properties

@@ -1,10 +1,10 @@
-slf4jVersion=1.7.2
+slf4jVersion=1.7.7
+guavaVersion=17.0
 jlineVersion=2.11
 junitVersion=4.11
-springVersion=4.0.3.RELEASE
-commonsioVersion=2.3
+springVersion=4.0.6.RELEASE
+commonsioVersion=2.4
 hamcrestVersion=1.3
 version=1.1.0.BUILD-SNAPSHOT
-cglibVersion=2.2.2
-mockitoVersion=1.8.5
-hamcrestDateVersion=0.9.3
+mockitoVersion=1.9.5
+hamcrestDateVersion=0.9.3