VPS private networks and firewall resources, parallel DNS update support

• Private network resources for VPS added, thanks to @JoooostB
• Firewall resource for VPS added, thanks to @kevinvalk
• Multiple DNS resources can now be updated without requirements of -parallelism=1, thanks to @kevinvalk
• Updated to Terraform SDK, @kevinvalk

REST API Support

This version has been refactored to use the new REST API instead of the deprecated SOAP/XML API.

Minor changes include:

• Support for token authentication
• base64installtext support for VPS resource
• VPS attribute processors renamed to cpus
• More tests
• Switched to Gomodules

Add more DNS record types (@nickboltjes)

0.0.7

Added SSHFP record type

Build against latest gotransip and Terraform 0.12.0

0.0.6

Mark tests terraform 0.12 compatible.

Add Vps resource

Still needs to be thoroughly tested.

Add retry logic to better handle concurrent API requests.

Closes #1

github actions workflow test

0.0.3

Test release upload

0.0.2

Add build script

0.0.1

Add build status