0.80.0

New release, many fixes, one breaking change to ParallelSSHClient.get_output.

• Getting output for hosts that have errors is now possible without stopping command executions on all hosts. Host exception is now returned in output when stop_on_errors=False - #32. See updated documentation of run_command. This has required a breaking change to ParallelSSHClient.get_output which will need updating if it is being used directly. Before: get_output(output). Now: get_output(output, greenlet). No changes are necessary if using ParallelSSHClient.run_command as recommended.
• Host de-duplication in output - #32
• Fix for lack of stdout causing client to hang - #37
• Host logging now disabled by default - #29. Call pssh.utils.enable_host_logging() to enable.
• Refactored module into separate packages, pssh.exceptions, pssh.pssh_client et al.
• Fake server used for testing renamed to embedded server and gained shell support - #24