Implement basic functionality of publish.

Implement basic functionality of publish with unittests and gitlab CI.

requested review from @m.hock

assigned to @hannes.mayr

added 1 commit

• 49855487 - Exception for linting because line of base64 encoded test picture is too long.

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added 1 commit

• a93bf070 - Fix last linting errors.

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added 1 commit

• 733b232c - Add module docstrings.

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mentioned in commit a60887a4

merged