BUG: Fix using "inf"/"-inf" in na_values for csv with int index column
- [x] closes #17128
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

The issue happens when you try to use 'inf' or '-inf' as part of na_values in read_csv.

Code snippet to reproduce:
```
from StringIO import StringIO

import pandas as pd

dataset = StringIO('''index,col1,col2,col3
1,6,10,14
2,7,11,15
3,8,12,16
4,9,13,17
5,inf,-inf,bla
''')
na_values = ['inf', '-inf', 'bla']

df = pd.read_csv(dataset, na_values=na_values, index_col='index')
print df
print df.dtypes
```

Without fix:
```
Traceback (most recent call last):
  File "/home/modintsov/workspace/DataRobot/playground.py", line 39, in <module>
    df = pd.read_csv(dataset, na_values=na_values, index_col='index')
  File "/home/modintsov/.virtualenvs/dev/local/lib/python2.7/site-packages/pandas/io/parsers.py", line 678, in parser_f
    return _read(filepath_or_buffer, kwds)
  File "/home/modintsov/.virtualenvs/dev/local/lib/python2.7/site-packages/pandas/io/parsers.py", line 446, in _read
    data = parser.read(nrows)
  File "/home/modintsov/.virtualenvs/dev/local/lib/python2.7/site-packages/pandas/io/parsers.py", line 1036, in read
    ret = self._engine.read(nrows)
  File "/home/modintsov/.virtualenvs/dev/local/lib/python2.7/site-packages/pandas/io/parsers.py", line 1922, in read
    index, names = self._make_index(data, alldata, names)
  File "/home/modintsov/.virtualenvs/dev/local/lib/python2.7/site-packages/pandas/io/parsers.py", line 1426, in _make_index
    index = self._agg_index(index)
  File "/home/modintsov/.virtualenvs/dev/local/lib/python2.7/site-packages/pandas/io/parsers.py", line 1520, in _agg_index
    arr, _ = self._infer_types(arr, col_na_values | col_na_fvalues)
  File "/home/modintsov/.virtualenvs/dev/local/lib/python2.7/site-packages/pandas/io/parsers.py", line 1600, in _infer_types
    mask = algorithms.isin(values, list(na_values))
  File "/home/modintsov/.virtualenvs/dev/local/lib/python2.7/site-packages/pandas/core/algorithms.py", line 418, in isin
    values, _, _ = _ensure_data(values, dtype=dtype)
  File "/home/modintsov/.virtualenvs/dev/local/lib/python2.7/site-packages/pandas/core/algorithms.py", line 82, in _ensure_data
    return _ensure_int64(values), 'int64', 'int64'
  File "pandas/_libs/algos_common_helper.pxi", line 3227, in pandas._libs.algos.ensure_int64
  File "pandas/_libs/algos_common_helper.pxi", line 3232, in pandas._libs.algos.ensure_int64
OverflowError: cannot convert float infinity to integer
```

With fix (as expected):
```
       col1  col2  col3
index
1       6.0  10.0  14.0
2       7.0  11.0  15.0
3       8.0  12.0  16.0
4       9.0  13.0  17.0
5       NaN   NaN   NaN
col1    float64
col2    float64
col3    float64
dtype: object
```