ENH: add the Edgeworth expansion based on the normal distribution

Given a set of cumulants, construct a matching distribution
as an asymptotic series starting from the normal distribution.
MAINT: make it work with scipy < 0.13
TST: remove an overly optimistic test
MAINT: remove hermite compat wrapper for numpy < 1.6
DOC: add a note to release notes
MAINT: distributions: tweak the __init__
TST: Test GEE with missing.
STY: Remove docstrings from tests
TST: Uncomment and fix original missing data tests
ENH: Handle missing for extra data with formulas
ENH: Workaround patsy NA handling. Closes #805.
TST: Regression test for ols formula and NA category
TST: Test that raise on NA with formula is possible
Merge pull request #1325 from ev-br/edgeworth

ENH: add the Edgeworth expansion based on the normal distribution
MAINT: Remove deprecated ARMA order argument
MAINT: Remove deprecated names argument.
MAINT: Remove deprecated confint argument.
MAINT: Remove from deprecated namespace
MAINT: Remove deprecated methods/attributes.
MAINT: Remove deprecated KDE class