Release dataverse 0.3.9

[kuriwaki]

First release:

• usethis::use_cran_comments()
• Proof read Title: and Description:
• Check that all exported functions have @returns and @examples (fixed in dev and others noted in Unused and unbuilt functions  #106 )
• Check that Authors@R: includes a copyright holder (role 'cph')
• Check licensing of included files
• Review https://github.com/DavisVaughan/extrachecks

Prepare for release:

• devtools::build_readme()
• urlchecker::url_check()
• devtools::check(remote = TRUE, manual = TRUE)
• devtools::check_win_devel()
• rhub::check_for_cran()

Submit to CRAN:

• usethis::use_version('patch')
• devtools::submit_cran()
• Approve email

Wait for CRAN...

• Accepted 🎉
• usethis::use_github_release()
• usethis::use_dev_version()
• Update install instructions in README