DOC: clean-up docstrings of sql
DOC: fix sql docs (write example data to database)
clarified to_excel and read_excel

as discussed in issue GH6260
. io.rst: added a paragraph explaining the difference in behaviour from
0.12
. excel.py: added docstring for has_index_names
thanks to jmcnamara and jorisvandenbossche
CLN: Convert last of assert_(x == y) to assertEqual

Work on #6175. Fixes last of vanilla assert_(x == y) conversions in pandas/tests and pandas/*/tests. Tests still pass locally.
CLN: Convert assert_(x != y) to assertNotEqual

Work on #6175. Converts instances in pandas/tests and pandas/*/tests. Tests still pass locally.
ENH: pytables start/stop/selection fixes and select_as_mutlipe change

This commit fixes issues with start/stop and selection. Furthermore
select_as_mutlipe is implemented differently:
- select_column and remove now hanlde start/stop arguments
- select_as_multipe hanldes start/stop the same way as select
- select_as_coordinates and select_column works with where expressions
  that result in filters. This also fixes select_as_multipe with filters
- select_as_multipe table iterator is rewritting, so memory usage is
  constant.

select_as_multiple now will always throw a KeyError if either a key or
the selector is not found.

Also closes GH4835
Merge pull request #6177 from wabu/selection-start-stop-fixes

ENH: select column/coordinates/multiple with start/stop/selection
BLD: update iron cache secure ids
BLD: iron cache secure ids try again
BLD: iron cache update third time is the charm
BLD: import error on py2.6 for print_versions
Merge pull request #6302 from iled/doc

DOC: clarified to_excel and read_excel (GH6260)
Merge pull request #6298 from jorisvandenbossche/sql-docstring

DOC: clean-up docstrings of sql + fix doc build
Added assert_numpy_array_equals to make assert statments in this
be easy to understand.
Merge pull request #6315 from KTAtkinson/issue_6175

BUG: #6175 Got rid of assert_ statements in test_algos.py
Merge pull request #6308 from bwignall/assert_6175_7

CLN: Convert last of assert_(x == y) to assertEqual
BUG: Regression in join of non_unique_indexes (GH6329)
Merge pull request #6330 from jreback/align

BUG: Regression in join of non_unique_indexes (GH6329)
BUG: Issue with groupby agg with a single function and a a mixed-type frame (GH6337)
Merge pull request #6338 from jreback/agg

BUG: Issue with groupby agg with a single function and a a mixed-type frame (GH6337)