Support dplyr 1.0

As of v0.3.0, RTD requires dplyr 1.0+. It doesn't change RTD interfaces itself, but you need to care about dplyr changes.

Support bulkd import without embulk

This version includes new features like bulk import REST API support for uploading data frames.

See also NEWS.md for detailed info.

Because RTD depends on msgpack not published on CRAN, we stopped releasing RTD on CRAN from v0.2.0.