Make inner classes static in http code

Static classes are preferrable to keep unwanted dependencies away, 
and they have one less member field.

Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>

org.eclipse.jgit.http.test/tst/org/eclipse/jgit/http/test/AsIsServiceTest.java

@@ -112,7 +112,7 @@ public void testCreate_Enabled() throws ServiceNotEnabledException,
 		service.access(new R("bob", "1.2.3.4"), db);
 	}
 
-	private final class R extends HttpServletRequestWrapper {
+	private static final class R extends HttpServletRequestWrapper {
 		private final String user;
 
 		private final String host;

org.eclipse.jgit.http.test/tst/org/eclipse/jgit/http/test/DefaultReceivePackFactoryTest.java

@@ -174,7 +174,7 @@ public void testCreate_Enabled() throws ServiceNotEnabledException,
 		assertNotNull("have ReceivePack", rp);
 	}
 
-	private final class R extends HttpServletRequestWrapper {
+	private static final class R extends HttpServletRequestWrapper {
 		private final String user;
 
 		private final String host;

org.eclipse.jgit.http.test/tst/org/eclipse/jgit/http/test/DefaultUploadPackFactoryTest.java

@@ -136,7 +136,7 @@ public void testCreate_Enabled() throws ServiceNotEnabledException,
 		assertSame(db, up.getRepository());
 	}
 
-	private final class R extends HttpServletRequestWrapper {
+	private static final class R extends HttpServletRequestWrapper {
 		private final String user;
 
 		private final String host;