cluster: removed array of regions due to they could be changed

[PacoDw]

closes #157

[shum]

LGTM. We can defer the error handling to the API endpoint.

[PacoDw]

Thank you so much @shum !

[marinsalinas]

LGTM!

[kostyazgara]

Can you say me, when changes will be applied in terraform provider and I can use them?

[PacoDw]

@kostyazgara I think the new release coming in the next week, but for now, you can use the master branch to use this new change, to use it you can follow these steps:

• Download the repository, make the following command to create the binary: go build
• Once you get the binary you can cut and paste in your project root. (I think you will need to remove the release with you are working)
• Later make: terraform init and that's it.
  Note: When the new release is done, you need to remove the current binary and make 'terraform init' to download automatically the last plugin version.