Swap the saharaclient and savannaclient directories

Exchange the contents of the saharaclient and savannaclient directories
so that 'savannlient' is the effective alias and 'saharaclient' contains
all of the source code.

* Change all of the imports that reference savannaclient to saharaclient
* Change paths that reference savannaclient (under doc)
* Leave variable and class names unchaned at this point
* Leave references to python_savannaclient unchanged since the top
* level dir name has not yet changed

Partial-implements: blueprint savanna-renaming-client
Change-Id: I83cb21922ae5a8cec291990b3ab67bb9e3cb2d62
Merge "Swap the saharaclient and savannaclient directories"