to_csv ignoring index=False (v0.22.0 only)
#### Code Sample, a copy-pastable example if possible

```python
            df.to_csv(output_path,
                       sep='\t',
                       header=False,
                       index=False,
                       float_format='%d'
                       )

```
#### Problem description

In Pandas v0.19 and 0.20 the above code would result in a tab-separated file, without an index column.

In v0.22 the index column is printed regardless of the index flag.

#### Expected Output
.tsv file without index column

#### Output of ``pd.show_versions()``

<details>
INSTALLED VERSIONS
------------------
commit: None
python: 2.7.11.final.0
python-bits: 64
OS: Linux
OS-release: 2.6.32-573.26.1.el6.x86_64
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_CA.UTF-8
LOCALE: None.None

pandas: 0.22.0
pytest: None
pip: 10.0.0
setuptools: 38.5.1
Cython: 0.28.2
numpy: 1.14.2
scipy: None
xarray: None
IPython: None
sphinx: None
patsy: None
dateutil: 2.7.0
pandas_gbq: None
pandas_datareader: None
</details>
