to_html w/ float_format="%.0f" renders 100.0 as 1
#### Code Sample, a copy-pastable example if possible

```python
import pandas as pd
print(pd.DataFrame([100.0]).to_html(float_format='%.0f'))
```
#### Problem description
The above code will render a value of 1 instead of 100.

```html
<table border="1" class="dataframe">
...
      <td>1</td>
...
</table>
```
#### Expected Output
```html
<table border="1" class="dataframe">
...
      <td>100</td>
...
</table>
```
#### Output of ``pd.show_versions()``

<details>

INSTALLED VERSIONS                                                                                                                                                                             [0/1850]
------------------
commit: None
python: 2.7.5.final.0
python-bits: 64
OS: Linux
OS-release: 3.10.0-123.20.1.el7.x86_64
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: None.None

pandas: 0.23.4
pytest: None
pip: 18.0
setuptools: 39.1.0
Cython: 0.23.4
numpy: 1.14.0
scipy: 1.0.0
pyarrow: 0.9.0
xarray: None
IPython: 5.6.0
sphinx: None
patsy: 0.5.0
dateutil: 2.6.1
pytz: 2018.3
blosc: None
bottleneck: None
tables: 3.4.2
numexpr: 2.6.2
feather: 0.4.0
matplotlib: 1.4.3
openpyxl: 2.4.9
xlrd: 0.9.3
xlwt: 1.0.0
xlsxwriter: 0.9.6
lxml: 3.4.2
bs4: 4.6.0
html5lib: 1.0.1
sqlalchemy: 1.0.12
pymysql: None
psycopg2: 2.6.1 (dt dec pq3 ext)
jinja2: 2.8
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None
</details>
