add filtering support of infeasible(None) objective value
add constraint filtering support of paretofilter and add constrained example of single_objective ei with constraint
minor error modifications
Merge remote-tracking branch 'origin/dev' into dev
Merge remote-tracking branch 'origin/dev' into dev
Merge remote-tracking branch 'origin/dev' into dev
test works
Merge pull request #1721 from cwmine/dev

add constraint filtering support for paretofilter and modified constrained  single_objective_ei to test it
Merge branch 'dev' of https://github.com/OpenMDAO/OpenMDAO-Framework into dfd
Merge branch 'dfd' of github.com:Kenneth-T-Moore/OpenMDAO-Framework into dfd
graph bug fix