Allow AWS EBS volume size and type to be set via config.
Allow AWS EBS volume size and type to be set via config.
Merge branch 'aws-ebs-config' of github.com:ministryofjustice/cotton into aws-ebs-config

Conflicts:
	cotton/provider/aws/driver.py
Merge pull request #35 from ministryofjustice/aws-ebs-config

Allow root AWS EBS volume size and type to be set via config.