Update Manageability page, include screenshot

Add coverage of management endpoints

Add cloud-init mention

Signed-off-by: Don Marti <dmarti@cloudius-systems.com>
Add link to Management include on home page

Signed-off-by: Don Marti <dmarti@cloudius-systems.com>
Add link to "Zero OS Management" section

Signed-off-by: Don Marti <dmarti@cloudius-systems.com>
Merge pull request #98 from dmarti/dashboard

First step on more manageability info