BUG: GEE partial cleanup of cov_type, see #1906
BUG/TST: GEE fix predict closes #1919 and fix conf_int for cov_params_default
add GEE to generic test, and adjust those (missing _results, summary2)
REF: GEE summary remove covariance_type argument (not possible)
BUG: GEE subclasses cov_params_default doesn't get attached, unit tests
TST: test_glm: remove test noise
REF: rename covariance_type -> cov_type
REF: GEE rename naive_covariance -> cov_naive, same for others
BUG/ENH: add df_resid, df_model, fixes t_test, closes #1918
BUG: NominalGEE fix initialization for pandas, closes #1931
ENH: GEE add Wrapper, closes #1904
BUG: NominalGEE pandas handling, fix typo, adjust unit tests
REF: GEEResults rename to postfix names, keep old as alias for now
TST: avoid pandas in assert with wrapped results (failure pandas>0.12)
Merge pull request #1924 from josef-pkt/bug_gee_cov_type_1906_rebased

BUG/REF gee cov type and other fixes