Add support for data without a spatial componenet

[mvanbommel]

The app currently assumes any data set will have a spatial component. Instead, there should be a check for a spatial component and if one does not exist, the app should switch over to the data tab and disable the map tab (likely with a way to inform the user the data set does not have a spatial component - maybe a tooltip on the map tab?).

Example data set: HR Payroll Data

  list(name = "HR Payroll Data",
       api = "https://services5.arcgis.com/54falWtcpty3V47Z/arcgis/rest/services/payroll/FeatureServer/0",
       url = "http://data.cityofsacramento.org/datasets/1884a7c3c1df47839ff582a267a1fcee_0")