BLD: add python 3.4 build on travis

BLD: remove statsmodels from 3.4 build

BLD: allow pip/setuptools to work on latest versions

BLD: install nose from master on EXPERIMENTAL builds
Merge pull request #7009 from jreback/python3.4

BLD/TST: Python3.4 testing via travis
BUG: fixing tseries plot cursor display, resolves #5453
Added selection example to cookbook

I added a (for me) very helpful Q&A from Stackoverflow on groupby/minimization while retaining the original DataFrame columns. Additionally, I cleaned up some links in the same cookbok section.

(Disclaimer: this is my first pull request.)
Merge pull request #7012 from ojdo/patch-1

Added selection example to cookbook
DOC: cookbook.rst corrections
ENH: Area plot is now supported by kind='area'. Also, line plot and area plot can be stacked by stacked=True.
TST: fixup test in tseries/test_offsets for test_datetimeindex (was using a current date)
TST: tests for groupby not using grouper column, solved in GH7000, (GH5614)
CLN: fix invalid line in test_offsets.py
Merge pull request #7019 from jreback/groupby_tests

TST: tests for groupby not using grouper column, solved in GH7000, (GH5614)
Merge pull request #6656 from sinhrks/area_pr2

ENH/VIS: Area plot is now supported by kind='area'.
Merge pull request #7007 from rosnfeld/issue_6623

BUG: fixing tseries plot cursor display, resolves #5453
ENH: support pie plot