Applied patch to sftp that searches for ssh keys in default locations
Typo fix
S3FS: correct verifying of buckets when IAM policy is applied.

This fixes Issue 120.
Added closing context manager to files returned by open
Fixed backref exception
Typo fix
Stop WrapFS unit tests throwing a RemoveRootError. Fixes Issue 121
Rename test classes from *ZipFS to *ArchiveFS
Fix Issue 122
Added python-libarchive to tox dependencies. Fixes Issue 123
Another removal of removedir("/")
Whole bunch of Python3 str->bytes fixes
Looks like closing() was being used incorrectly. Fixes Issue 124
Re-enable the SFTP nosetests. Seems like the latest version of paramiko no
longer has the problems we were encountering before. Also required a quick
fix to SFTPFS.removeddir(..., recursive=True)
No need to save original_setcontents in fakeOn - it's already done in setUp.
Found and fixed some more sneaky Python3 str->bytes problems
Refactored/simplified the compatibility.copy_file_to_fs function.
Doh! ReadOnlyFS was blocking delattr and not delxattr
Removed ZipFS reference (copy/paste error).
Forgot to add BackReferenceError to __all__ list. This caused problems in expose/sftp.py (BackReferenceError not defined).