Added support for multiple VPCs in ec2_vpc module

Added support for multiple VPCs with the same CIDR block - provided tags are used to uniquely name/identify a VPC resource.  

We use VPCs as containers for environments or stacks such as Dev, QA, DevOps, Demo, etc.  They are identical in content and use the same network configuration such as CIDR blocks, IP address ranges, etc.   To differentiate between them we tag (via Ansible, btw) each resource including the VPC with a short code of the stack it represents: DEV, SIT, DMO, etc. and release/build number.  

By the way, Amazon no longer offers EC2-Classic environments.