Customise metadata and filter options in GeoNode

[JamesSample]

We should agree on a standard set of SeaBee-specific metadata attributes and decide which are mandatory and which are optional. As far as possible, we should stick to existing metadata standards and keep the mandatory fields fairly minimal (at least initially).

The GeoNode UI should then be customised to show the main attributes relevant to SeaBee, rather then the current default setup.

We should also customise the filtering and search options. For example, it would be useful to be able to filter based on mission date (i.e. specify a time interval of interest), which is not currently available on our GeoNode.

@deviirmr - Can you consider what customisations are feasible/fairly easy, please?

@JamesSample - Compile initial suggestions for metadata attributes

[deviirmr]

@JamesSample: Since some of the filters have already been implemented on the GeoNode GeoViz page, such as date, mission type, etc., and relevant metadata is displayed in the popup info on click, do we need to put in any further effort on this thread, or should it be closed?