function get_species_list fails for countries with no species

[bluehill]

Example:
get_species_list("egypt")
Error in guess_header_(datasource, tokenizer, locale) :
Cannot read file C:/Users/Alan Lee/AppData/Local/Temp/RtmpQ71ZDZ/file6078395bae: The volume for a file has been externally altered so that the opened file is no longer valid.

Strongly suggest that at least in the beta version this call should be restricted to southafrica (and or surrounding southern african countries), nigeria, kenya: all other countries have very small numbers of contributions.

valid_countries <- c("kenya", "southafrica", "nigeria", "botswana", "namibia", "zimbabwe", "lesotho", "swaziland", "mozambique")

example addition if(country !%in% valid_countries) {
stop(message = "Sorry; currently this call is only supported for Kenya, Southern Africa and Nigeria")
}

[davidclarance]

Good point. Will add a catch error.