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__
DOC: Silence fit.
ENH: Allow user to control formula namespace depth.
DOC: Add eval_env to documentation.
DOC: Add eval_env note to release notes.
DOC: What it is what it is.
Merge pull request #2031 from jseabold/patsy-env

ENH: Expose patsy eval_env to users.
Merge pull request #2032 from jseabold/update-readme

DOC: What it is what it is.
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