added command to update route53 record

[taraspos]

Added command to update route53 record (or create if not exist).

Use case: self-registration of the ec2 instance on route53, with the ability to rewrite existing record.

Implemented by using Route53 API native UPSERT action.

[fxaguessy]

Hi, Thanks for this contribution, it is a good idea to add such a feature. I have a few comments before accepting the changes:

• In order to generate the files beginning with gen_, run the command go generate gen/aws/generators/main.go. You don't have to write these files manually. (You will see that the generated files are a bit different than yours).
• As the the Update_Record and Create_Record are very similar, but not generated code, I propose to remove code duplication:
  1. For the DryRun, in Update_Record_DryRun body, call Create_Record_DryRun
  2. For the real execution, in Update_Record and Create_Record (and perhaps also in Delete_Record) extract a method building the input and performing the ChangeResourceRecordSets call, taking as input params map[string]interface{} and action string. This method will be wrapped in Update_Record Create_Record and Delete_Record with their specific code.

[taraspos]

@fxaguessy thanks for your suggestions, I just updated the PR

[fxaguessy]

Great ! Merged in master, it will be in next release. Thanks @Trane9991 for your contribution.

As we try to focus awless on broad practical usage, it would be great if you could have a look at this form: https://goo.gl/forms/1lQFPEIxdt37aDn43