Update to Spring Boot 1.4

Fixes gh-4050

build.gradle

@@ -9,7 +9,7 @@ buildscript {
 		classpath('me.champeau.gradle:gradle-javadoc-hotfix-plugin:0.1')
 		classpath('org.asciidoctor:asciidoctor-gradle-plugin:1.5.1')
 		classpath("io.spring.gradle:docbook-reference-plugin:0.3.1")
-		classpath("org.springframework.boot:spring-boot-gradle-plugin:1.3.3.RELEASE")
+		classpath("org.springframework.boot:spring-boot-gradle-plugin:1.4.0.RELEASE")
 	}
 }
 

samples/boot/insecure/build.gradle

@@ -5,8 +5,8 @@ springBoot {
 }
 
 dependencies {
-    compile "org.springframework.boot:spring-boot-starter-web:1.3.3.RELEASE",
-            "org.springframework.boot:spring-boot-starter-thymeleaf:1.3.3.RELEASE"
+    compile "org.springframework.boot:spring-boot-starter-web",
+            "org.springframework.boot:spring-boot-starter-thymeleaf"
 
-    testCompile "org.springframework.boot:spring-boot-starter-test:1.3.3.RELEASE"
+    testCompile "org.springframework.boot:spring-boot-starter-test"
 }