forested 0.2.0

• The first version of the package just had data from Washington, called
  forested. The second release of the package also includes data from Georgia.
  The forested data is the same as it was, and now is aliased as forested_wa.
  The data from Georgia is called forested_ga. The Georgia data has the same
  structure, except is missing the northness variable due to issues with the
  source raster. forested_ga also includes a new variable county
  (#18, h.t. @graysonwhite).

• forested and its alias forested_wa gained a new variable, county (#14).