Various fixes/imporvements to jsnoop.common.archives module

* hasattr checks for properties and cleanup functions replaced with
* try/catch
* cleanup now correctly called on del of AbstractArchive instances
* cleanup method now made internal
* added comments for is_tarfile and is_archive methods
* made all implementations of AbstractArchive behave similarly for
* extract/extract_all
* extract_all now has force_file_obj parameter to specify that we want
* file-like-objects instead of file paths when dealing with stuff
* on-disk
* file_to_bio mehtod added to convert files on disk to BIO
* fileobjects created from ondisk directories now give empty BIO object
* for sanity
* native archives now correctly return list of
* filepaths/file-like-objects