WIP: Resolve "Support recordings"

Closes #6

added source::customer label

added 6 commits

• a9f38378 - Implement most of recording dataclasses
• f6fce092 - Fix generation of attendees list in meeting dict
• 276686cb - Merge branch 'master' into 6-support-recordings
• 6b06bcb8 - Implement dict converters for preview image
• d5e505f2 - Simplify value access
• 97271cee - Align stripping of attribute names in all objects

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added 9 commits

• 97271cee...cab89722 - 8 commits from branch master
• 56f29854 - Merge branch 'master' into 6-support-recordings

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