test(integration): add an app deploy test for `deis pull`
feat(contrib/ec2): always deploy into VPC; support all instance types

This commit rewrites our CloudFormation template for EC2. This includes
the following changes:
* Create a new VPC by default; existing VPC support is left as-is
* Support all EC2 instance types
* Support both PV- and HVM-virtualized AMIs

This also eliminates the 'No default VPC for this user' error that was
the result of not having a default VPC in the region.
docs(README.md): clarify current release and encourage use of master
ref(*): move ADD command to bottom

This effectively lets us cache the VOLUME, WORKDIR, EXPOSE, etc.
entries whenever we make changes to the components, speeding up local
development compilation.
Merge pull request #1502 from deis/optimize-builder

ref(*): move ADD command to bottom
Merge pull request #1572 from deis/doc-current-version

docs(README.md): clarify current release and encourage use of master
Merge pull request #1559 from deis/1434-test-deis-pull

test(integration): add an app deploy test for `deis pull`
Merge pull request #1564 from deis/deploy_deis_to_vpc

feat(contrib/ec2): always deploy into VPC; support all instance types