bugfix for some scipy NLP solvers (unconstrained)

Another one bugfix have been committed (appered due to some recent svn changes for scipy_cg, scipy_ncg, scipy_powell, scipy_bfgs, scipy_fminbound).
Thanks to Nils Wagner for reporting the issue.
That one was due to definition of exception "isSolved" migrated from BaseProblem.py to ooMisc.py