Adding optional extra tags

[MattiasGees]

Is this a BUG REPORT or FEATURE REQUEST?:

Uncomment only one, leave it on its own line:

/kind bug

/kind feature

What happened:
No way to provide extra tags to AWS resources

What you expected to happen:
I want to add extra tags to my AWS resources because some tags should be the same over my environment while Kubernetes independent. These tags would be added to the AWS resources we create with Tarmak:

• AWS Instances
• Subnets
• VPC
• ELB
• EBS volumes

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:
Maybe we can add some extra config to the tarmak.yaml file to let users define extra tags?

Environment:

• Kubernetes version (use kubectl version):
• Cloud provider or hardware configuration**:
• Install tools:
• Others: