Allow newlines in data passed to to_gbq()

[cbandy]

Relates to #180.

I intended to include \r\n in the system test, but I found that something was stripping \r in the round trip:

>       assert result_df.iloc[2,0] == "ij\r\nkl"
E       AssertionError: assert 'ij\nkl' == 'ij\r\nkl'
E         - ij
E         + ij
E         ?   +
E           kl

The unit test shows, I think, that we're sending the values correctly, so I didn't investigate further.

[stickler-ci]

The following files do not match the black styleguide:

• tests/system/test_gbq.py
• tests/unit/test_load.py

[max-sixty]

This looks great, thanks @cbandy !

Would you mind formatting with black? We're using that for consistent formatting now. LMK if you need any guidance

[cbandy]

@max-sixty fixed in amended commit! thanks.

[tswast]

Thanks!

[max-sixty]

Thanks @cbandy (and thanks @tswast for catching, I'm not sure why I missed that notification)