changing check_config to be called everywhere before execution of model
interface update
small fix
fix for distsim
removed the 'required' metadata from the 'best_case' Slot in expected_improvement
small fix to FixedPointIterator
Merge pull request #1302 from naylor-b/check_config

check_config is now called for the whole hierarchy below the executed component
Merge branch 'dev' into gui