REF: use bfgs, one fails to converge
with starting values (forgot to commit basic bfgs version)
(small difference in prob starting values makes bfgs converge, one degenerates?)
ENH/REF:  add bins options, change to original number of bins (fit plot looks much better)
adjustments to fit and example
chisquare test for n_components=1, cdf_mix may need fix for this case
BUG/ENH/TST: mixture_von_mises add tests, allow 1 component, bugs, closes #3 closes #4
DOC: smaller changes to example (run only 1 case), 1 typo fixed
ENH: add normalize params (ex_cdf written some time ago, needs to be moved)
DOC: add plot of length distribution to example file