rerddap 0.2.0

NEW FEATURES

• Added a suite of functions to manage local cached files (#17)

MINOR IMPROVEMENTS

• Added new ERDDAP server to list of servers in the servers() function (#21)

BUG FIXES

• Fixed a few cases across a number of functions in which an empty list
  passed to query parmaeter in httr::GET() caused an error (#23)
• Fixed retrieval of path to file written to disk by httr::write_disk() (#24)
• last is a value accepted by ERDDAP servers, but internal functions
  weren't checking correctly, fixed now. (#25)
• as.info() wasn't passing on the url parameter to the info() function.
  fixed now. (#26)