Try to make Jetty scan TLDs in nested JARs

Jetty apparently does it differently (different version of
Jasper maybe), so you need a unique jarFileURL for each
nested JAR (previously they were all set to the parent
archive URL).

Also added the root of the main archive as a valid
document root.

For gh-367

spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/JarFileTests.java

@@ -150,6 +150,8 @@ public class JarFileTests {
 		assertThat(jarURLConnection.getContentLength(), greaterThan(1));
 		assertThat(jarURLConnection.getContent(), sameInstance((Object) this.jarFile));
 		assertThat(jarURLConnection.getContentType(), equalTo("x-java/jar"));
+		assertThat(jarURLConnection.getJarFileURL().toString(), equalTo("jar:file:"
+				+ this.rootJarFile));
 	}
 
 	@Test
@@ -212,8 +214,10 @@ public class JarFileTests {
 		URL url = nestedJarFile.getUrl();
 		assertThat(url.toString(), equalTo("jar:file:" + this.rootJarFile.getPath()
 				+ "!/nested.jar!/"));
-		assertThat(((JarURLConnection) url.openConnection()).getJarFile(),
-				sameInstance(nestedJarFile));
+		JarURLConnection conn = (JarURLConnection) url.openConnection();
+		assertThat(conn.getJarFile(), sameInstance(nestedJarFile));
+		assertThat(conn.getJarFileURL().toString(), equalTo("jar:file:"
+				+ this.rootJarFile.getPath() + "!/nested.jar"));
 	}
 
 	@Test
@@ -304,7 +308,6 @@ public class JarFileTests {
 	}
 
 	@Test
-	@SuppressWarnings("resource")
 	public void verifySignedJar() throws Exception {
 		String classpath = System.getProperty("java.class.path");
 		String[] entries = classpath.split(System.getProperty("path.separator"));