read_sas crashes when reading time data
read_sas works just fine with my other tables. I suspect this may have something to do with converting timeseries or timedeltas, given the nature of the error message and the fact that this only happens with a table that contains time series.

####

```python
> df = pd.read_sas(filename,encoding='utf-8')

```
#### 

```
  File "<ipython-input-119-402090ec994d>", line 1, in <module>
    vehicle = pd.read_sas('C:/Users/aliceell/Documents/schemas/new_mexico/dr527_veh_1214.sas7bdat',format='sas7bdat',encoding='ISO-8859-1')

  File "C:\Users\aliceell\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\sas\sasreader.py", line 61, in read_sas
    return reader.read()

  File "C:\Users\aliceell\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\sas\sas7bdat.py", line 589, in read
    rslt = self._chunk_to_dataframe()

  File "C:\Users\aliceell\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\sas\sas7bdat.py", line 634, in _chunk_to_dataframe
    rslt[name] = epoch + pd.to_timedelta(rslt[name], unit='d')

  File "C:\Users\aliceell\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\util\decorators.py", line 91, in wrapper
    return func(*args, **kwargs)

  File "C:\Users\aliceell\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\tseries\timedeltas.py", line 90, in to_timedelta
    values = _convert_listlike(arg._values, box=False, unit=unit)

  File "C:\Users\aliceell\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\tseries\timedeltas.py", line 78, in _convert_listlike
    _ensure_object(arg), unit=unit, errors=errors)

  File "pandas\tslib.pyx", line 2933, in pandas.tslib.array_to_timedelta64 (pandas\tslib.c:52393)

  File "pandas\tslib.pyx", line 3253, in pandas.tslib.convert_to_timedelta64 (pandas\tslib.c:55946)

  File "pandas\tslib.pyx", line 3598, in pandas.tslib.cast_from_unit (pandas\tslib.c:61059)

OverflowError: int too big to convert

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

<details>
pd.show_versions()
C:\Users\aliceell\AppData\Local\Continuum\Anaconda3\lib\site-packages\matplotlib\__init__.py:1401: UserWarning:  This call to matplotlib.use() has no effect
because the backend has already been chosen;
matplotlib.use() must be called *before* pylab, matplotlib.pyplot,
or matplotlib.backends is imported for the first time.

  warnings.warn(_use_error_msg)

INSTALLED VERSIONS
------------------
commit: None
python: 3.5.2.final.0
python-bits: 64
OS: Windows
OS-release: 7
machine: AMD64
processor: Intel64 Family 6 Model 37 Stepping 5, GenuineIntel
byteorder: little
LC_ALL: None
LANG: en

pandas: 0.18.1
nose: 1.3.7
pip: 9.0.1
setuptools: 27.2.0
Cython: 0.24.1
numpy: 1.11.1
scipy: 0.18.1
statsmodels: None
xarray: None
IPython: 5.1.0
sphinx: 1.4.6
patsy: 0.4.1
dateutil: 2.5.3
pytz: 2016.6.1
blosc: None
bottleneck: 1.1.0
tables: 3.2.2
numexpr: 2.6.1
matplotlib: 2.0.0
openpyxl: 2.3.2
xlrd: 1.0.0
xlwt: 1.1.2
xlsxwriter: 0.9.3
lxml: 3.6.4
bs4: 4.5.1
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: 1.0.13
pymysql: None
psycopg2: None
jinja2: 2.8
boto: 2.42.0
pandas_datareader: None
</details>


I'm on Windows 7 64-bit.

Google's giving me nothing. It's difficult for me to provide sample data because I don't actually have SAS and so anything I provide would have to be run through pandas or R or something similar to convert it to a CSV, potentially overwriting whatever's causing the bug. But if you think it would be helpful, I can do that.