Now uses pxssh to work better with ssh

Now also checks return value of each command
Improved README and examples
Added exit value in config

Added return_value option in config to define passing/failing return values for a command.
Also added command_timeout support for each command
Added 3 connect attempts to a host before aborting
Added sleep option to wait in conf

Also handles errors in print class better.
If job is aborted before a job has connected, it will now properly abort the job
Added sphinx documentation
Catching SystemExit to acoid stacktrace on -h option
Handle string as sleep argument
Updated docs
Added cleanup option on hosts
Added possibility to run jobs with custom created session jobs from a script
Added better error message when config file contains errors
Fixed bug in last commit where command args failed to parse
Added check for minimum required version of pexpect
Fixed bugs with Terminal log and print options

* terminal.log was incorrectly deleted
* print-commands option did not work
* Added --no-terminal-output to disable all output to terminal
Added option to send sigint before closing ssh connection
Added options --resume and --name

Using the options --resume and --name it's possible to resume
a previously aborted session from where it was stopped
Added better separation between different tests setups
Fix bug where test crash if job_index is not specified in session_job_conf