Use rodents data

[njtierney]

Inspiration: https://allisonhorst.shinyapps.io/missingexplorer/

Data sources:

• http://lter.konza.ksu.edu/content/csm08-small-mammal-host-parasite-sampling-data-16-linear-trapping-transects-located-8-lter
• https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-knz&identifier=99&revision=5

[njtierney]

Resolved in #5