Remove dependency to audfactory

[frankenjoe]

Closes #50 #90

• The dependency to audfactory is removed and a dependency to dohq-artifactory is set instead
• The functions to authenticate and download / deploy an artifact are extracted from audfactory and modified accordingly
• Authentication is done only once when the backend is created and re-used afterwards
• The path of the config file can now be set via ARTIFACTORY_CONFIG_FILE

[codecov]

Codecov Report

Merging #106 (584fe0f) into dev (14a568d) will not change coverage.
The diff coverage is 100.0%.

Impacted Files	Coverage Δ
audbackend/core/artifactory.py	100.0% <100.0%> (ø)

[hagenw]

Great, I think we made big progress regarding future proof with the Artifactory backend by no longer requiring audfactory and raising always the same error if there is an error happening on the backend