Delete ktbs_bench package

This package will be externalised as ktbs_bench_manager.
Change ref from ktbs_bench to ktbs_bench_manager

Previously, ktbs_bench was python module inside this project.
It has been moved outside into an indenpendant python package named ktbs_bench_manager.

Notes: the file that fixes blank nodes insert in store is no longer provided, you must put it
in the rdflib package (i.e. `rdflib/plugins/stores/bnsparqlstore.py`).
Add `ktbs_bench_manager@master` as a requirement

Also change `sutils` requirement version from a sha to branch master.
Fix logging not being displayed in console anymore
Add dependency docopt for bench.py script
Merge branch 'pkg-bench-manager'