274: Service provider: Create

[tlake]

What does this pull request do? Implements the Create operation for the Service Provider.

How should this be tested?

• Confirm that the api unit tests pass
  • go test ./... from layer0/api/
• Confirm functionality through Swagger
  • go run main.go from layer0/api/
  • Use http://localhost:9090/api/?url=/swagger.json to create a service, both with and without a loadbalancer
    • Make sure to convert the contents of a Dockerrun.aws.json file to base64: openssl base64 -in <infile>
• Confirm that other service operations function upon services created by this changeset (i.e. can you use Swagger to read a service you've created?)

Checklist

• [x] Unit tests
• ~[ ] Smoke tests (if applicable)~
• ~[ ] System tests (if applicable)~
• [ ] Documentation (if applicable)

closes # (reference the issue(s) this pull request closes)