Add planned content blocks and functionality stubs

For Documentation and Trainings we need some streamlined user interface, even when not all functionality is implemented yet.

Shows Tab:

• Content block with past "Emissions" / or a separate top-level navigation item "Emissions" holding future & past emissions. The current tab called emissions could be called "Calendar" (It's seen by Programme Coorindators only, anyway)
• Button for "Download Recording"
• Button for "Upload to CBA"