Remove purrr dependency

[mhpob]

A few helper functions were made to be vectorized by using purrr::map. This PR:

• lightly refactors the helper functions to be "vectorized" by internal use of sapply
• removes dependency on purrr (following Simplify GLATOS dependencies, especially plyr #122)
• adds unit tests for the helper functions
• re-builds blue_shark_att to address convert_otn_to_att test expects "NA" to be a factor level. #240

[mhpob]

Bit by #237. Wrapped the payload of query_worms_common in list to replicate the output of purrr::map when multiple scientific names match common names.

[mhpob]

On hold until #240 is resolved.