Typo in BQ Standard SQL samples.

[tswast]

The parameter is useLegacySql not useLegacySQL. See:
https://code.google.com/p/google-bigquery/issues/detail?id=701

I also update the tests to use a query that only works with standard SQL
for those tests.

[theacodes]

@dpebot please merge when travis passes

[dpebot]

Okay! I'll merge when all statuses are green.

[tswast]

@jonparrott The Travis failure seems unrelated to this change. Pip can't install the cryptography library.

  Running setup.py bdist_wheel for cryptography: finished with status 'error'
  Complete output from command /home/travis/build/GoogleCloudPlatform/python-docs-samples/.nox/travis-subsession-tests/bin/python3.5 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-i5ug1jdx/cryptography/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" bdist_wheel -d /tmp/tmp7v1a65_2pip-wheel- --python-tag cp35:
  c/_cffi_backend.c:2:20: fatal error: Python.h: No such file or directory

[theacodes]

@tswast I fixed that in master, your branch might not have picked it up. I'll merge anyway.