Allow refresh auto config to be disabled by property.

fixes gh-276

spring-cloud-context/src/main/java/org/springframework/cloud/autoconfigure/RefreshEndpointAutoConfiguration.java

@@ -65,6 +65,7 @@ public class RefreshEndpointAutoConfiguration {
 	protected static class RefreshEndpointConfiguration {
 
 		@Bean
+		@ConditionalOnBean(ContextRefresher.class)
 		@ConditionalOnEnabledEndpoint
 		@ConditionalOnMissingBean
 		public RefreshEndpoint refreshEndpoint(ContextRefresher contextRefresher) {