use different opt config strategy (goncalotomas#218)

* use different opt config strategy

* log different message when no adapter is used

implement concurrent drivers for greater throughput (goncalotomas#215)

* use pool of drivers to increase concurrency

* improve error logging

* update antidote docker image

* update deps, small tweaks to drivers

* remove unsupported drivers

* fix bugs in adapter and ets driver

* update erlang release to be used in travis

* delete obsolete modules