moved solver interface impl under cyclus namespace
moved solver interface impl under cyclus namespace

Baaaaam/cyclus,hodger/cyclus,mbmcgarry/cyclus,gidden/cyclus,hodger/cyclus,rwcarlsen/cyclus,mbmcgarry/cyclus,gidden/cyclus,Baaaaam/cyclus,gidden/cyclus,hodger/cyclus,hodger/cyclus,mbmcgarry/cyclus,rwcarlsen/cyclus,gidden/cyclus,Baaaaam/cyclus,hodger/cyclus,rwcarlsen/cyclus,rwcarlsen/cyclus,mbmcgarry/cyclus