Changes from 0.2.x:
- package name changed to `dwave-cloud-client`
- code refactored and split into submodules under the `dwave.cloud` namespace
- introduced the concept of D-Wave resources (QPU sampler, software sampler)
- new configuration format and scheme (`dwave.conf` in cwd, user-local, system-wide locations)
- legacy code removal (SAPI emulation) and clean-up
- major and minor bug fixes