Add `upload_rm` file transfer option

Similar to `ln_rm`, this first performs a remote upload
and then deletes the file locally if the upload and hash
check were successful.
Fix up error logging
Remove sphinx.environment.BuildEnvironment and sphinx.util.relative_uri

This feature does not work for now
Fix docstrings of omero.callbacks
Fix omero __init__.py header
Fix docstrings in omero.gateway

Should remove all warnings when building the sphinx-api
Fix docstring of omero.install.versions
Fix docstring in omero.util.import_candidates
Fix docstring in omero.util.populate_roi
Fix docstring in omero.util
Merge pull request #2803 from joshmoore/rebased/develop/upload-rm

Add `upload_rm` file transfer option (rebased onto develop)
Merge pull request #2910 from sbesson/rebased/develop/sphinxapi_compilation

Fix warnings in Sphinx API generation (rebased onto develop)