use switch instead of if, and case insensitize

[bransonf]

• switch is better practice/cleaner than many else if's
• enforcing capitalization can be frustrating and is unnecessary

[chris-prener]

I'm happy to make the "switch" (made myself laugh) but this PR seems to have broken all of the unit testing on here.

[bransonf]

I’ll investigate.

[bransonf]

Forgot to lint first time around, but I fixed the missing comma.

As far as why Appveyor is failing, the configuration doesn't have testthat or covr installed since they're only suggests:

[chris-prener]

No, the suggests is all that is needed I believe. I'll have to look into this...

[bransonf]

Once you download the zip with the logs from appveyor, it errors that it can’t test because the packages to do so are missing. I think it’s more so an appveyor configuration thing than a package thing.