ENH: add statsmodels wheel

Also removes the statsmodels/pandas faking part of ci/install.sh by using a
statsmodels wheel
CLN: proper version checking for statsmodels testWLS
BUG/ENH: provide better .loc based semantics for float based indicies, continuing not to fallback (related to GH236)

API: stub-implementation of Float64Index (meaning its the 'same' as an Index at this point), related GH263

BUG: make sure that mixed-integer-float is auto-converted to Float64Index

BUG: (GH4860), raise KeyError on indexing with a float (and not a floating index)

CLN/ENH: add _convert_scalar_indexer in core/index.py

CLN/ENH: add _convert_slice_indexer in core/index.py

TST: slice indexer test changes in series/frame

BUG: fix partial multi-indexing

DOC: release notes / v0.13.0
TST: tests for doc example

CLN: core/indexing.py clean
DOC: add to indexing.rst

DOC: small corections

API: make Float64Index getitem/ix/loc perform the same (as label based) for scalar indexing

TST: Float64Index construction & tests

TST: misc tests corrected in test_series/test_reshape/test_format

TST: Float64Index tests indexing via lists

DOC: additional example for float64index
Merge pull request #4981 from cpcloud/statsmodels-ci-addition

CI/ENH: test against an older version of statsmodels
API: properly box numeric timedelta ops on Series (GH4984)
Merge pull request #4985 from jreback/timedelta1

API: properly box numeric timedelta ops on Series (GH4984)
Merge pull request #4850 from jreback/loc_float

BUG/ENH: provide better .loc based semantics for float based indicies, continuing not to fallback (related GH236)
BUG: Bug in concatenation with duplicate columns across dtypes not merging with axis=0 (originally GH4771),
     fixed again is (GH4975)
Merge pull request #4989 from jreback/merge_er

BUG: Bug in concatenation with duplicate columns across dtypes, GH4975
ENH: Make categorical repr nicer.

ENH: Support printing empty categorical.

TST: Add tests for categorical printing.

REF: Remove unnecessary unicode calls.

TST: Hack so tests pass with numpy < 1.7.x

CLN: fix DataFrame import in core/categorical.py
Merge branch 'dt_index_fix' of https://github.com/filmor/pandas into filmor-dt_index_fix

Conflicts:
	doc/source/release.rst
Merge pull request #4944 from engstrom/master

DOC: Added to docstrings in factorize function GH2916
Merge branch 'issue-4678-thousands-date-conflict' of https://github.com/guyrt/pandas into guyrt-issue-4678-thousands-date-conflict

Conflicts:
	doc/source/release.rst
CLN: fix py2to3 issues in categorical.py
Merge pull request #4990 from jreback/cat_fix

CLN: fix py2to3 issues in categorical.py
TST: fix indexing test for windows failure
Merge pull request #4992 from Komnomnomnom/indexing-dtype-test-fix

TST: fix indexing test for windows failure
BUG: Fix appending when dtypes are not the same (error showing mixing float/np.datetime64) (GH4993)
Merge pull request #4995 from jreback/nat_append

BUG: Fix appending when dtypes are not the same (error showing mixing float/np.datetime64 (GH4993)
API: Remove deprecated Factor (GH3650)