Fixes #82

* Ensures the S3 VPC Endpoint association is only created if there are public subnets

Fixes #89

* Ensures a single DDB association in the public route table

Removed aws_default_route_table and aws_main_route_table_association, added potentially failed example (#111)

* Extended aws_vpn_gateway use case

* Fixed warning from outputs on vgw_id

* Added possibility to create VPC conditionally

* Added editorconfig and pre-commit hooks

* Manage Default Route Table under Terraform

- With name
- And Tags

* Use `aws_default_route_table` instead

* Added aws_main_route_table_association resource

* Update main.tf

* Adding base-level tests for simple-example

* gitignoring test kitchen internals

* incorporating feedback from newcontext folks

* comment clean up before PR

* upgrading to kt 3.1.x

* test repaired for kt 3 compat

* removing the gemfile lock

* making md linter happy and adjusting content to match test fixture

* PR feedback and rubocop compliance

* Issue #56: Added tags for elastic ips

* add cidr_block outputs to public and private subnets

* add cidr_block outputs to database and elasticache subnets

* add redshift subnet option

* fix tag

* add missing route association for redshift

* add vpc_endpoint_s3_pl_id and vpc_endpoint_dynamodb_pl_id outputs

* add redshift to complete-vcp example

* fix domain_name_servers - keep it a list

* fix outputs for TF 0.11

* fix missing *

* Minor corrections in example and in type of dhcp_options_domain_name_servers

* Minor corrections in example

* Updated README

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* Added fix for issue when no private subnets are defined

* Minor readme

* Allow passing in EIPs for the NAT Gateways

* Document how to pass external IPs for NAT Gateways

* Update README.md to reduce example code

Outputs directly referencing resource IDs that are only conditionally
created are not valid. Use the concat * trick to make sure we always
have a valid value for these outputs.

* Add support for DHCP options set

* code cleanup

* remove unnecessary depends_on in aws_vpc_dhcp_options_association definition