AmbiguousTimeError: Cannot infer dst time from Timestamp('2015-11-01 01:00:03'), try using the 'ambiguous' argument
In Pandas 0.19.0, there seems to be an error when setting the timezone for times close to the dst cutoff. 

This issue appears very similar to #11619 and #11626, both of which have been closed. The traceback is below. 

``` python
df['Timestamp'] = df['Timestamp Date'] + " " + df['Timestamp Time']
df['Timestamp'] = pd.to_datetime(df['Timestamp']).dt.tz_localize('US/Central')

---------------------------------------------------------------------------
AmbiguousTimeError                        Traceback (most recent call last)
 in ()
----> 1 df['Timestamp'] = pd.to_datetime(df['Timestamp']).dt.tz_localize('US/Central')

/Users/adam/anaconda/lib/python2.7/site-packages/pandas/core/base.pyc in f(self, *args, **kwargs)
    208 
    209             def f(self, *args, **kwargs):
--> 210                 return self._delegate_method(name, *args, **kwargs)
    211 
    212             f.__name__ = name

/Users/adam/anaconda/lib/python2.7/site-packages/pandas/tseries/common.pyc in _delegate_method(self, name, *args, **kwargs)
    130 
    131         method = getattr(self.values, name)
--> 132         result = method(*args, **kwargs)
    133 
    134         if not is_list_like(result):

/Users/adam/anaconda/lib/python2.7/site-packages/pandas/util/decorators.pyc in wrapper(*args, **kwargs)
     89                 else:
     90                     kwargs[new_arg_name] = new_arg_value
---> 91             return func(*args, **kwargs)
     92         return wrapper
     93     return _deprecate_kwarg

/Users/adam/anaconda/lib/python2.7/site-packages/pandas/tseries/index.pyc in tz_localize(self, tz, ambiguous, errors)
   1823             new_dates = tslib.tz_localize_to_utc(self.asi8, tz,
   1824                                                  ambiguous=ambiguous,
-> 1825                                                  errors=errors)
   1826         new_dates = new_dates.view(_NS_DTYPE)
   1827         return self._shallow_copy(new_dates, tz=tz)

pandas/tslib.pyx in pandas.tslib.tz_localize_to_utc (pandas/tslib.c:70327)()

AmbiguousTimeError: Cannot infer dst time from Timestamp('2015-11-01 01:00:03'), try using the 'ambiguous' argument
```

Here is some relevant information on the data frame. 

```
df[['Timestamp Date', 'Timestamp Time', 'Timestamp']].head()
  Timestamp Date Timestamp Time               Timestamp
0     01-04-2016    07:10:03 AM  01-04-2016 07:10:03 AM
1     01-04-2016    07:20:04 AM  01-04-2016 07:20:04 AM
2     01-04-2016    07:30:03 AM  01-04-2016 07:30:03 AM
3     01-04-2016    07:40:03 AM  01-04-2016 07:40:03 AM
4     01-04-2016    07:50:03 AM  01-04-2016 07:50:03 AM

df.info()
<class 'pandas.core.frame.DataFrame'>
RangeIndex: 286834 entries, 0 to 286833
Timestamp Date       286834 non-null object
Timestamp Time       286834 non-null object
Timestamp            286834 non-null object
```

I also had this same issue in Pandas 0.18.0 before upgrading to 0.19.0.
