Dwavebinarycsp

Changes
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* Drop support for Python 2.7 and 3.4

New Features
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* Uses the new `penaltymodel-lp` library for penalty models without auxiliary variables.

New Features
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* Make use of penaltymodel 0.16.x

New Features
-------------------
* Support for dimod 0.8.x

Bug Fixes
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* Fix case sensitive environment marker values in setup for windows

Changes:

- penalty model factory availability check deferred until import and first use (not during install; works with wheels)

Changes:

- installer change: decision on which penaltymodel is installed deferred to caller (user or the parent package) via 'extras'
- docs update