Initial Release

• removal of go-tf-run (outdated go-tfe dependency)
  • use current go-tfe
  • incorporate go-tf-run functionality
• remove directory upload functionality (not sure what it is used for, I just want to trigger a run)
• remove custom tf-var functionality because it was bound to the dir upload functionality. Could be implemented by using new API provided by go-tfe
• fix bug: fails if an terraform output is not a JSON string
• fix docu: wrong defaults in readme
• security issue: do not log sensitive outputs