Careful with default serialization, JBVFS-17

[starksm64]

The serialization of the NestedJarFromStream is incorrect. Its using default serialization of these fields:

private transient ZipInputStream zis;
private URL jarURL;
private URL entryURL;
private long lastModified;
private long size;
private AtomicBoolean inited = new AtomicBoolean(false);

The problem is that the inited flag should not be serialized as this implies its parents fields:

private transient List entries;
private transient Map<String, VirtualFileHandler> entryMap;

have been initialized. They will not be after deserialization of NestedJarFromStream as it lazily does initialization. We need to be careful when adding fields to a class that is using the default java serialization contract.

[alesj]

Serialization for nested jars is broken anyway.
See the problem that I somehow hinted about in AbstractJarHandler.handleJarFile.

The thing is that when you do

 JarURLConnection jconn = (JarURLConnection) conn;
 jar = jconn.getJarFile();

on an url that points to nested jar, you're gonna get only the first non-nested jar.
And doing jar.getEntry(current.getName()) on it, will return null, or the wrong entry (in case the names are accidentally equal).