PR for 0.2.5 release

[wnojopra]

This release includes:

• "Retrying" output messages are more informative.
• script and script-name now appears in dstat.
• Docker entrypoints changed to '/usr/bin/env' to allow bash images to work.
• pyyaml version updated to latest version allowing Python3.7 support.
• google-v2 provider updates:
  • --nvidia-driver-version parameter can now be used to specifiy the NVIDIA driver version to use when attaching an NVIDIA GPU accelerator.