Tags (key>value) interface for properties

[mjaquiery]

Is your feature request related to a problem? Please describe.
File data are neatly decomposed into columns and their values. A similar approach would be valuable for the properties of cell families, cells, equipment, etc. etc..

Describe the solution you'd like
Cells, equipment, etc. should have a list of properties that can be applied (some recommended as semi-mandatory), optionally with a list of values they could take.

Additional context

• Metatable of Properties: name, (data) type, applies_to (cell family, equipment, etc), display_order, recommended, suggested_values
• UI for editing properties
• Adapt API data definitions to move non-required properties to Property interface
• Adapt display of cell family, equipment etc. pages to best implement properties.
• Support searching/filtering of objects by their properties

Would also close #80

[mjaquiery]

More thought needed as to how to present this, how to strike a balance between ease-of-entry and addition of metadata, and how and whether this ties in with JSON-LD proposals #95

[mjaquiery]

This is going to form a part of #118 as we bring in JSON-LD-backed minimal JSON schemas for validating metadata.