Initial implementation
Check for default-vpc is none
Merge branch 'master' of https://github.com/juju/juju into ec2-defaultvpc
Use defaultVpc method
Test SupportAddressAllocation
Use const for none
Merge pull request #931 from voidspace/ec2-defaultvpc

Implement SupportAddressAllocation for ec2

We support static ip address allocation (the SupportAddressAllocation capability on environ) for ec2 if we have a default vpc.