strip spaces from start/end of params in add backend
remove unsupported arg by current paramiko version
Merge pull request #305 from mistio/paramiko_remove_banner

remove unsupported arg by current paramiko version
Merge pull request #302 from mistio/strip_add_backend_args

strip spaces from start/end of params in add backend
Remove core_wrapper
Merge pull request #306 from mistio/remove_core_wrapper

Remove core_wrapper