extend /report to multi-sites

[ericnost]

EJAM is designed for evaluating multiple sites at once, rather than one lat/long pair.

Modify the API /report endpoint to handle multiple lat/longs, shapes, or FIPS.

[ericnost]

This is already possible with the /data endpoint and might work in some cases for /report but haven't tested

[ericnost]

#24 is related

[ericnost]

Based on https://github.com/ejanalysis/EJAM/blob/9a8e6508815df66542e089bbf3f013d5b69f3856/R/ejam2report.R#L8 test removing the site number parameter completely...or, to address #24 as well, something like:

sitenumber as a param in the /report endpoint, defaults to null

create a param "count" that counts how many input sites/fips/shapes there are.

In the to_map section, test whether sitenumber is null. Set to_map based on sitenumber if not null (to_map$ejam_uniq_id <- sitenumber). If sitenumber is null and count = 1, set to_map$ejam_uniq_id <- 1. Not sure what to do if sitenumber is null and there are multiple sites. I think all of this only applies in the shapes case.

in the ejam2report call, set sitenumber to sitenumber

^ This assumes a null sitenumber will produce valid output regardless of whether the input to ejam2report is one site or multiple