Low, low priority: Consider alternate handling for encrypted Zip streams

[tballison]

In this example file: https://github.com/apache/tika/blob/master/tika-parsers/src/test/resources/test-documents/testZipEncrypted.zip, one of the streams is encrypted, and the other isn't.

It might be useful to report an encrypted stream in the output json and then process the unencrypted file type rather than throwing an exception on the file and not processing it at all.