Added properly functioning case insensitive match without regex

pandas.core.strings.str_contains should now match case insensitivity properly if given regex=False and case=False.  Also added test cases for case insensitive pandas.core.strings.str_contains with and without regex.
Documentation for str_contains bug in changelog
BUG: grouped hist and scatter use old figsize default
BUG: single column bar plot is misaligned
BUG: Better xaxis handling for partial layout
Redesigned pandas.io.gbq to remove bq.py as a dependency for everything except unit testing. Minor API changes were also introduced.
Squashed commit of the following:

commit 5e9e0fa29d727953583a116638a9d0db81f9ed21
Author: Michael Mueller <michaeldmueller7@gmail.com>
Date:   Thu Jun 26 19:53:35 2014 -0400

    Fixed issue with empty lines

commit 57b54918b251ab77f000b575d77bcce3affcb27a
Author: Michael Mueller <michaeldmueller7@gmail.com>
Date:   Thu Jun 26 16:31:27 2014 -0400

    Added reference to new functionality in docs

commit a2371638691584416439d3c6a4dd2ef1829dcbe3
Author: Michael Mueller <michaeldmueller7@gmail.com>
Date:   Thu Jun 26 16:26:06 2014 -0400

    Implemented functionality to ignore comment lines, wrote a test
BUG/TST: fix tests for groupby nth on Series (GH7559)
TST: Change nose.SkipTest to raise nose.SkipTest for io.data.Options.
Merge pull request #7598 from dstephens99/master

TST: Change nose.SkipTest to raise nose.SkipTest for io.data.Options.
ENH: look for index columns in row after header
BUG: DTI.freqstr raises AttributeError when freq is None
BUG: PeriodIndex.min/max returns int
Merge pull request #7606 from sinhrks/freqstr

BUG: DTI.freqstr raises AttributeError when freq is None
Merge pull request #7609 from sinhrks/pminmax

BUG: PeriodIndex.min/max returns int
API: DatetimeIndex and PeriodIndex have same representation
Merge pull request #7602 from sinhrks/periodrepr

API: DatetimeIndex and PeriodIndex have same representation
Removing Python2.6 CI dependencies to test import failures
Fix typo in documentation

Signed-off-by: Julien Danjou <julien@danjou.info>
Merge pull request #7613 from jd/master

Fix typo in documentation