v0.92: several improvements

- improved handling executors
- stopped starting new run if there is already a run for given stage
- added sending ping to db in case of storage service to prevent
  using stale connections

v0.91

removed pylxd from agent requirements.txt as it is not portable

v0.90

removed docker from agent requirements.txt as it is not portable

v0.89

fixed publishing artifacts to github

v0.88

improved releasing

v0.87

added intallation and updating of kraken agent

v0.86

This is the first public release.