Fix compilation error

Author: graemerocher

grails-gradle-plugin/src/main/groovy/org/grails/gradle/plugin/core/GrailsGradlePlugin.groovy

@@ -41,6 +41,7 @@ import org.gradle.api.tasks.TaskContainer
 import org.gradle.api.tasks.bundling.Jar
 import org.gradle.api.tasks.compile.GroovyCompile
 import org.gradle.api.tasks.testing.Test
+import org.gradle.language.jvm.tasks.ProcessResources
 import org.gradle.process.JavaForkOptions
 import org.gradle.tooling.provider.model.ToolingModelBuilderRegistry
 import org.grails.build.parsing.CommandLineParser