rnoaa v1.3.0

NEW FEATURES

• ghcnd() now accepts more than 1 station identifier (#373) PR from @eliocamp
• ersst(): use new v5 version of their service - see ?ersst docs for details (#381) thanks @vonStadarhraun for the tip

MINOR IMPROVEMENTS

• update buoy() docs to state that a special value of 9999 passsed to the year parameter will give the most up to date data (aka current data) - and an example added using it (#377)
• update to current dplyr functions from deprecated ones (#375)
• update description of units TMAX and TMIN for dataset GHCND when using function ncdc() with add_units = TRUE (#378) (#379) PR from @amcdavid

BUG FIXES

• changed ghcnd() handling of unknown/bad/invalid station identifiers: now returns an empty data.frame and gives back empty strings for the two attributes source and file_modified (#374)