fixed as.uid error

[zachary-foster]

Description

Uses the same method as my last PR. Still need to change to the tt with an API key default of NULL version, but this works for now at least.

Related Issue

resolves #674

Example

> as.uid(315567)
No ENTREZ API key provided
See https://ncbiinsights.ncbi.nlm.nih.gov/2017/11/02/new-api-keys-for-the-e-utilities/
[1] "315567"
attr(,"class")
[1] "uid"
attr(,"match")
[1] "found"
attr(,"multiple_matches")
[1] FALSE
attr(,"pattern_match")
[1] FALSE
attr(,"uri")
[1] "https://www.ncbi.nlm.nih.gov/taxonomy/315567"

[sckott]

nice, thanks, good catch