Cassandra-snap

* add support for restore backups from S3

* add support for password authentication

* Use cqlsh to backup schema instead of depreciated cassandra-cli
* AWS IAM role support
* lzop decompression for the restore command
* add argument to pass an SSH key file
* Get --keyspaces working with multiple keyspaces
* Fixing sstableloader path and data directory for recovery
* Added exclude tables option
* Make upload_file robust against failures of all kinds
* Added support for S3 reduced redundancy and S3 upload speed limiter

* Use sudo on cassandra nodes only if --use-sudo option is provided
* Adjust buffer size for S3 uploads (match with compressed fragments)
* Added support for cassandra mutilple data directory
* Removed --data-path cmdline option
* Added --conf-path cmdline option (tells where cassandra.yml is located)

* Fix bug with missing manifest file on S3 (--prefix)

* Configurable SSH port
* Change agent put from multiprocessing to threading
* Upload retries
* Cleanup failed multipart uploads (remove parts from S3)
* Add upload timeout (fails if uploading 60MB takes more than 600s)
* Use ssh config