BUG: Fix to_datetime to properly deal with tz offsets #3944

Currently for certain formats of datetime strings, the tz offset will
just be ignored.
BUG: fix broken BigqueryError reference
Replace network decorator with with_connectivity_check

Network decorator was ignoring test failures due to API changes in
external services.
DOC: clarify that ExcelFile is not deprecated but only moved (GH5435)
ENH get_dummies str method

FIX/DOC py3 and add docstrings

DOC add in get_dummies to release and docs
PERF speed up str.get_dummies
DOC add str.get_dummies to api
BLD: travis reports job names to ScatterCI
BLD: travis reports job names to ScatterCI
Add Scatter-CI link to README.md
PERF: fix JSON performance regression from 0.12 (GH5765)
DOC: v0.13.1.txt updates
BLD: use newer versions of numexpr with numpy 1.8
BUG: Bug in DataFrame construction with recarray and non-ns datetime dtype (GH6140)
ENH: Add unique and nunique to GroupBy whitelist

Series.unique and Series.nunique are useful methods for querying the
unique elements (or number of unique elements) in each group when used
in conjunction with DataFrame.GroupBy.  This commit addresses
pydata/pandas#6146.
ENH: Updated tests for series GroupBy whitelist

Added tests for fix to pydata/pandas#6146.
CLN: fix ScatterCI links in README and rnotes
CLN: convert test docstring to comment
BLD/TST: catch more spurious errors in @network decorator
BLD/TST: one more skip_errno for @network