Rename Chef Metal to Chef Provisioning

Wasn't sure about this sucker, though:

WAS:
`{ "metal": { "location": { ... }}}`

NOW:
`{ "provisioning": { "location": { ... }}}`

Assuming that's correct?
Update faq as per @jkeiser's advice
Merge pull request #216 from kanerogers/patch-1

Rename Chef Metal to Chef Provisioning