Bump python-savannaclient to 0.5.0

* it's first release with CLI covering mostly all features
* dev docs moved to client from the main repo
* support for all new Savanna features introduced in Icehouse release cycle
* single common entrypoint, actual - savannaclient.client.Client('1.1)
* 93 commits from the prev. release

Change-Id: Ib00dd24aacbdea146fcf33b1ec9f62b1b0533f38