Updated/edited Image chapter.

Install: Added short intro. Turned steps into procedures.
  Fixed the credentials. Added note about using IP address.
  Commented out redundant config.
Verify: Added link to Virtual Machine Image Guide. Turned steps into procedure.
  Added info about -is-public value.

Change-Id: I27b8397957ac352b25e868d821e9c921d6ec80c9
Change build to built as appropriate

Florian Haas noticed wrong grammar in my text, fixed thus.

Change-Id: Ia839179da63f4adfc06088d74cbbd9fb104464f4
Merge "Updated/edited Image chapter."