v1.2.1
- COPY: treat absolute source paths as being relative to the contextdir (#191)
- COPY: treat sources named "" as "*" (#181/#190)
- dockerclient/testdata/copychown/Dockerfile: remove an irrelevant instruction (#189)
- dockerclient: implement --chown for ADD/COPY (#187/#188)
- README.txt: correct the suggested invocation for conformance tests (#185)