travis build fails with documentation check warnings

When building under Travis (https://travis-ci.org/ropensci/datapack/builds/325678968), we now see documentation warnings that were previously not present. These appear to be picking up a mismatch between NA_character in the code and as.character(NA) in the docs in function prototypes. Not sure why they are cropping up now. Looks like regenerating the docs could do the trick. Example from Travis output:

0.55schecking for code/documentation mismatches ... WARNING
Codoc mismatches from documentation object 'initialize,DataObject-method':
\S4method{initialize}{DataObject}
  Code: function(.Object, id = NA_character_, dataobj = NA, format =
                 NA_character_, user = NA_character_, mnNodeId =
                 NA_character_, filename = NA_character_, seriesId =
                 NA_character_, mediaType = NA_character_,
                 mediaTypeProperty = list(), dataURL = NA_character_)
  Docs: function(.Object, id = as.character(NA), dataobj = NA, format =
                 as.character(NA), user = as.character(NA), mnNodeId =
                 as.character(NA), filename = as.character(NA),
                 seriesId = as.character(NA), mediaType =
                 as.character(NA), mediaTypeProperty = list(), dataURL
                 = as.character(NA))

ropensci / datapack

travis build fails with documentation check warnings #98