Download one Acquia backup database at a time.

[becw]

See #103.

This removes the old Acquia database downloading targets in favor of a new task that downloads new backups selectively via the Acquia Cloud API.

To test:

• Download your Acquia Cloud API credentials and move them to ~/.acquia/cloudapi.conf on your Vagrant box
• Configure your Acquia site properties in .the-build/build.default.properties.yml:

  acquia:
    site: mysite
    realm: devcloud
  

• Run phing acquia-get-backup - the latest backup should be downloaded to artifacts/backups
• Run phing acquia-load-backup - the latest existing backup in artifacts/backups will be loaded in to the site db

[byrond]

@becw, this is a very elegant solution and a great improvement for downloading databases from Acquia! I just had a couple of issues during testing and some questions.

[becw]

@byrond I've fixed the bugs that you found and made the updates you suggested. I think we're ready to go now?

[becw]

Merging so that I can cut a new alpha tag.