Cran edits

[slager]

First batch of edits addresses the following issues identified during manual CRAN submission review:

• Please add \value to .Rd files regarding exported methods and explain the functions results in the documentation. Please write about the structure of the output (class) and also what the output means. (If a function does not return a value, please document that too, e.g.

\value{No return value, called for side effects} or similar) Missing Rd-tags:
      data_version.Rd: \value
      datapackage_skeleton.Rd: \value
      document.Rd: \value
      keepDataObjects-defunct.Rd: \value
      package_build.Rd: \value

• \dontrun{} should only be used if the example really cannot be executed (e.g. because of missing additional software, missing API keys, ...) by the user. That's why wrapping examples in \dontrun{} adds the comment ("# Not run:") as a warning for the user. Does not seem necessary.
  Please replace \dontrun with \donttest.
  Please unwrap the examples if they are executable in < 5 sec, or replace dontrun{} with \donttest{}.
  -> datapackager_object_read.R; document.Rd

• You are setting options(warn=-1) in your function. This is not allowed. Please rather use suppressWarnings() if really needed.
  -> R/digests.R