* added doc for parameter 'coerce_float' in io.sql.read_frame
adjusted the indentation of doc of io.sql.read_frame
fixed conflict in sql.py
ENH col_level argument to melt
ENH MultiIndex columns with melt
ENH add drop_na argument to pivot_table
CLN make cartesian product faster
DOC: Update excel read dependency on ``xlrd``

Since 98f65b19f918b825ae6cb1001cd8e91f45377cc7,
``xlrd`` handles reading both ``.xls`` and ``.xlsx`` Excel Files.
DOC: Update docstrings to reflect benefit from resolving #4131

1bd8f57d68686f268922a1e230c5a8f2e4e3cc9d resolves #4131 without
updating docstrings in relevant functions.  No way to know that keep_default_na
and verbose are valid keyword arguments without inspecting the parsers.py code
and documentation
BLD: use the wheel url for scikits timeseries
BUG/TST: wrong parsing of microseconds with format arg (#4152)
Merge pull request #4166 from jorisvandenbossche/bug-microsecond-parsing

BUG: wrong parsing of microseconds with format arg (#4152)
DOC: minor io/whatsnew doc edits
TST: to_datetime format fixes

CLN/TST: to_datetime cleanup

TST: tests for dayfirst=True
Merge pull request #4168 from cpcloud/sktimeseries-dl-fix

BLD: use the wheel url for scikits timeseries
Merge pull request #4167 from jreback/dt_format

TST: to_datetime format tests
DOC to_datetime warning about dayfirst strictness
TST: remove double call to yahoo finance
Merge pull request #4175 from hayd/datetime_dayfirst_warning

DOC to_datetime warning about dayfirst strictness
Merge pull request #4176 from cpcloud/remove-yahoo-test

TST: remove double call to yahoo finance