Upgrade to use xmlrpc 0.11.0

Add from_json helper and improve Error definition

Crate docstrings improvements

Restructure to make more coherent. Expose helpers in the crate

Improved error handling and code refactoring

0.6.0: Unambiguous host and better error handling

0.5.1: New version like 0.5.0, annotated to trigger binary release gen

Prepare for version 0.5.0

Signed-off-by: Marcello Seri <marcello.seri@citrix.com>

xapirpc: small naming change

Signed-off-by: Marcello Seri <marcello.seri@citrix.com>

xapirpc: move to 0.3.0 and rationalise cli

Signed-off-by: Marcello Seri <marcello.seri@citrix.com>