…erbutler into drop-box-slash-issue

* 'develop' of https://github.com/CenterForOpenScience/waterbutler: (77 commits)
  final cleanups for onedrive
  make provider readonly
  start cleaning up and reorganizing onedrive
  implement Microsoft OneDrive provider using dropbox as base
  added onedrive provider -- copied from Dropbox
  don't assume file metadata has a modified/created date
  add mypy type annotations
  add modified/created dates to file metadata
  expand docstrings
  add ruby serialization workaround to download
  clean up commit_sha vs. branch_name handling
  add tests for revisions and uninit-ed repos
  add artificial test for missing folder
  remove unused and obsolete code
  rewrite test suite for provider changes and coverage
  update some more docstrings on the provider
  GL provider is read-only: folder creation is not allowed
  add workaround for non-existent directories not being reported in GL
  document workarounds in download & _fetch_file_contents
  remove unneeded error wrapping from metadata
  ...

# Conflicts:
#	waterbutler/server/api/v1/provider/movecopy.py