Refactor Environment and PropertySource

* Environment now extends PropertyResolver
* Environment no longer exposes resolver and sources
* PropertySource is String,Object instead of String,String
* PropertySource no longer assumes enumerability of property names
* Introduced EnumerablePropertySource for those that do have enumerable property names

org.springframework.web/src/main/java/org/springframework/web/context/support/ServletConfigPropertySource.java

@@ -20,6 +20,7 @@ import java.util.Enumeration;
 
 import javax.servlet.ServletConfig;
 
+import org.springframework.core.env.EnumerablePropertySource;
 import org.springframework.core.env.PropertySource;
 import org.springframework.util.CollectionUtils;
 
@@ -30,7 +31,7 @@ import org.springframework.util.CollectionUtils;
  * @since 3.1
  * @see ServletContextPropertySource
  */
-public class ServletConfigPropertySource extends PropertySource<ServletConfig> {
+public class ServletConfigPropertySource extends EnumerablePropertySource<ServletConfig> {
 
 	public ServletConfigPropertySource(String name, ServletConfig servletConfig) {
 		super(name, servletConfig);

org.springframework.web/src/main/java/org/springframework/web/context/support/ServletContextPropertySource.java

@@ -20,6 +20,7 @@ import java.util.Enumeration;
 
 import javax.servlet.ServletContext;
 
+import org.springframework.core.env.EnumerablePropertySource;
 import org.springframework.core.env.PropertySource;
 import org.springframework.util.CollectionUtils;
 
@@ -30,7 +31,7 @@ import org.springframework.util.CollectionUtils;
  * @since 3.1
  * @see ServletConfigPropertySource
  */
-public class ServletContextPropertySource extends PropertySource<ServletContext> {
+public class ServletContextPropertySource extends EnumerablePropertySource<ServletContext> {
 
 	public ServletContextPropertySource(String name, ServletContext servletContext) {
 		super(name, servletContext);

org.springframework.web/src/main/java/org/springframework/web/filter/GenericFilterBean.java

@@ -27,7 +27,6 @@ import javax.servlet.ServletException;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-
 import org.springframework.beans.BeanWrapper;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.MutablePropertyValues;