Sshutils refactoring

Paramiko sftp client is not eventlet friendly. Also it doesn't work
with some servers, so upload/download methods has been removed.
Downloading or uploading can be done in other way (see examples).

Added ability to pass process stdin, which makes possible to
do on remote host anything at all.

Much more clean and usable API.

Change-Id: If357a2878c2c60646a975c386a0fe2f1616aec95
Add rally use command - part 2

This completes the behaviour of the 'rally use' command.
when the command is called, it creates a file called openrc-{deployid}
in ~/.rally/ which contains instructions to export deployment specific
environment variables

It also creates a symlink ~/.rally/openrc that refers to the latest
deployment called with 'rally use'

It becomes simple to just do 'source ~/.rally/openrc' and then
'nova list'

Implements blueprint: rally-use-command

Change-Id: I51ddfdbf7b8ab41b5b26685dd7b671468d306fe1
Merge "Sshutils refactoring"
Add display of atomic actions timer in CLI

Added a prettytable that prints detailed information about the
execution time of each atomic action.

Implements: blueprint time-measuring-of-atomic-actions
(Part "II) CLI" of time-measuring-of-atomic-actions)

Change-Id: I1558d324a92063db3bd3d09d67b0635b93390107
Mark task as failed if benchmark validation fails

Change-Id: Idab924ab51cdd30c232b620abf161af40f3e4ac2