Merge pull request #29 from dmcglinn/master

Include occurrenceID in query results from occurrencelist()
a number of small changes to fxns
Merge branch 'master' of https://github.com/ropensci/rgbif

Merging pull request from Dan McGlinn
tidied examples in occurrencelist and oc-many fxns
Merge remote-tracking branch 'upstream/master'