* 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 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
TST: Create a MySQL database and run MySQL tests on Travis.
TST: fix ujson tests failures on 32-bit
DOC: increased width of text area
DOC: update ipython_directive with changes from ipython to restart prompt number at 1 each page
Merge pull request #4154 from davidshinn/improve_excel_docs

DOC: Improve excel docs
Merge pull request #4106 from hayd/cartesian_crosstab

ENH: add dropna argument to pivot_table
DOC: more cookbook recipies
CLN: Ignore warnings generated by 'DROP TABLE IF EXISTS' when table does not exist.
Merge pull request #4068 from simomo/read_sql_enhencement

DOC: read_frame doc enhancement
BUG: (GH4192) Fixed buglet in the broadcasting logic in Series.where
BUG: (GH4192) fixed broken unit test
BUG: invert_xaxis (negative tot_sec) triggers MilliSecondLocator (#3990)
Merge pull request #4177 from danielballan/mysql-on-travis

TST: Do not skip MySQL tests on Travis.