TADA_DataRetrieval will not work for multiple states

[hillarymarler]

Describe the bug

If you try to query for more than one state, you receive this error message: Bad Request (HTTP 400).299 WQP "The value of statecode=US:NA must match the format (?:([A-Z]{2}):)?([0-9]{1,2})"
Error in attr(retval, "queryTime") <- Sys.time() :
attempt to set an attribute on NULL

To Reproduce

library(TADA)

R5 <- c("IL", "IN")


TADAProfile <- TADA_DataRetrieval(statecode = R5, 
                                  startDate = "2019-05-01", 
                                  endDate = "2019-05-07", 
                                  applyautoclean = FALSE)

Expected behavior

Return data from both IL and IN

Reminders for TADA contributors addressing this issue

New features should include all of the following work:

• Create the function/code.

• Document all code using comments to describe what is does.

• Create tests in tests folder.

• Create help file using roxygen2 above code.

• Create working examples in help file (via roxygen2).

• Add to appropriate vignette (or create new one).