Need better checks on terms cromwellQuery

[seandavi]

When specified as named vector, errors out. However, list works. Need to check value of terms.

y = cromwellQuery(terms=c(status='Succeeded'))
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 Error: 
4.
stop(sprintf("Cromwell API request failed [%s]\n%s\n<%s>", status_code(resp), 
    parsed$message, parsed$documentation_url), call. = FALSE) at api.R#77
3.
.cromwell_process_response(resp) at api.R#39
2.
cromwell_GET(path = path, query = terms) at api.R#125
1.
cromwellQuery(terms = c(status = "Succeeded"))