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
DOC: fix startrow typo in docstrings
ENH: Period supports NaT
Merge pull request #7485 from sinhrks/periodnat

ENH/BUG: Period/PeriodIndex supports NaT
BUG: Bug in Panel indexing with a multi-index axis (GH 7516)
Merge pull request #7521 from dsm054/fix-startrow-typo

DOC: fix startrow typo in docstrings
Merge pull request #7519 from jreback/mi2

BUG: Bug in Panel indexing with a multi-index axis (GH 7516)
REGR: Regression in datetimelike slice indexing with a duplicated index and non-exact end-points (GH7523)
Merge pull request #7525 from jreback/slice

REGR: Regression in datetimelike slice indexing with a duplicated index and non-exact end-points (GH7523)
BUG: DatetimeIndex comparison handles NaT incorrectly
Merge pull request #7529 from sinhrks/dtibool

BUG: DatetimeIndex comparison handles NaT incorrectly
CI: use cython 0.20.2 on py3.4
TST: io.data.Options changes to avoid test failures on bad data.

Added try, except to underlying price / quote_time function.

Changed to RemoteDataError in the event that some tables are found, but the correct table is not available.
BUG: Timestamp.tz_convert resets nanosecond
should fix issue #7520, test_nanargmin fails with datetime64 objects
Merge pull request #7535 from toddrjen/nandatetime

should fix issue #7520, test_nanargmin fails with datetime64 objects
Merge pull request #7534 from sinhrks/nanotz

BUG: Timestamp.tz_convert resets nanosecond
Merge pull request #7530 from dstephens99/master

TST: io.data.Options changes to avoid test failures on bad data.
ENH: allow read_excel to accept URLs (GH6809)