Exchange time in Info

Trying out the 2nd option in #51 (comment 228879)

• Add time property to info
• Use info time in connector for pushes and pulls, if no time is given
• Fix components and tests

Example component fixes for these changes: finam-netcdf!19 (merged)

Other changes:

• Rename connector parameter required_in_data to pull_data

Fixes #51 (closed)