Add bioswale exports

[steventlamb]

This should be handled by: 1) Zipping bioswale exports alongside tree exports such that IDs mentioned in the former can be found in the latter 2) Adding a column for tree counts per bioswale 3) adding a column for flattening a list of tree objects down to the following fields:

• id number
• species(?)
• diameter
• ... (add more fields) ...

[dboyer]

Bioswale exports should include:

• all bioswale data fields
• any stewardship actions logged for the bioswale
• number of trees in the bioswale
• for each tree in the bioswale include - id number (planting site or tree? whatever we include in exports), species, diameter