Clean up unnecessary gradle plugin application

'checkstyle' and 'pmd' are applied elsewhere and don't need to be applied at
the root level. 'maven' isn't needed here, and actually causes additional
artifacts to be generated that aren't needed.

build.gradle

@@ -65,13 +65,10 @@ checkstyle {
 
 configure(allprojects) {
 	group = "org.springframework.cloud"
-	
-	apply plugin: "maven"
+
 	apply plugin: "eclipse"
 	apply plugin: "idea"
 	apply plugin: "jacoco"
-	apply plugin: "pmd"
-	apply plugin: "checkstyle"
 	apply plugin: "propdeps"
 	apply plugin: "propdeps-idea"
 	apply plugin: "propdeps-eclipse"