smbclient and new threaded worker

• Dropped support for Python 2.6 and Python 3.4
• Added the smbclient package that provides a higher level API for interactive with SMB servers
• Deprecated smbprotocol.query_info in favour of smbprotocol.file_info, query_info will be removed in the next major release
• Add automatic symlink resolver when a symlink is in the path being opened
• Fix issue when trying to connect to host with IPv6 address
• Fix response parsing for SMB2 Create Response Lease V1 and V2
• Added the ability to set the Oplock level when opening a file
• Revamped the socket listener and message processor to run in a separate thread for faster message resolving
• Added the FileSystemWatcher in change_notify.py to provider a way to watch for changes on the SMB filesystem
• Added the .cancel() method onto a Request to cancel an SMB request on the server