Removed unused imports in GrailsApplicationPostProcessor

Author: ColinHarrington

grails-core/src/main/groovy/grails/boot/config/GrailsApplicationPostProcessor.groovy

@@ -37,9 +37,6 @@ import org.springframework.core.convert.converter.Converter
 import org.springframework.core.env.AbstractEnvironment
 import org.springframework.core.env.ConfigurableEnvironment
 import org.springframework.core.env.EnumerablePropertySource
-import org.springframework.core.env.MapPropertySource
-import org.springframework.core.env.PropertySource
-import org.springframework.util.ClassUtils
 
 /**
  * A {@link BeanDefinitionRegistryPostProcessor} that enhances any ApplicationContext with plugin manager capabilities