tz_localize fails in 0.19.1 even with ambiguous='infer'
Consider this timeseries:

```
0    2016-11-06 01:19:54.000
1    2016-11-06 01:34:52.000
2    2016-11-06 01:35:36.000
3    2016-11-06 01:28:25.000
4    2016-11-06 01:59:32.000
5    2016-11-06 01:26:53.000
6    2016-11-06 01:52:44.000
7    2016-11-06 01:07:09.000
8    2016-11-06 01:35:03.000
9    2016-11-06 01:11:19.000
10   2016-11-06 01:31:28.000
11   2016-11-06 01:10:16.000
12   2016-11-06 01:04:55.000
13   2016-11-06 01:07:16.000
14   2016-11-06 01:09:35.000
15   2016-11-06 01:11:50.000
16   2016-11-06 01:15:03.000
17   2016-11-06 01:03:23.000
18   2016-11-06 01:20:27.000
19   2016-11-06 01:17:20.000
20   2016-11-06 01:14:44.000
21   2016-11-06 01:14:32.000
22   2016-11-06 01:20:23.000
23   2016-11-06 01:31:55.000
24   2016-11-06 01:32:45.000
25   2016-11-06 01:32:52.716
26   2016-11-06 01:00:55.000
27   2016-11-06 01:03:52.262
28   2016-11-06 01:19:59.000
29   2016-11-06 01:32:36.000
30   2016-11-06 01:48:56.000
31   2016-11-06 01:49:06.000
32   2016-11-06 01:29:11.170
33   2016-11-06 01:29:51.745
34   2016-11-06 01:30:09.560
35   2016-11-06 01:38:12.432
36   2016-11-06 01:45:23.631
37   2016-11-06 01:51:52.046
38   2016-11-06 01:52:36.318
39   2016-11-06 01:10:58.000
Name: ts, dtype: datetime64[ns]
```

When I try to do:

```
> temp.dt.tz_localize('US/Eastern', ambiguous='infer')
```

I get:

```
AmbiguousTimeError: There are 13 dst switches when there should only be 1.
```

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

```
INSTALLED VERSIONS
------------------
commit: None
python: 3.5.2.final.0
python-bits: 64
OS: Darwin
OS-release: 16.1.0
machine: x86_64
processor: i386
byteorder: little
LC_ALL: en_US.UTF-8
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

pandas: 0.19.1
nose: 1.3.7
pip: 9.0.0
setuptools: 27.1.0.post20161104
Cython: 0.25.1
numpy: 1.11.2
scipy: 0.18.1
statsmodels: 0.6.1
xarray: None
IPython: 5.1.0
sphinx: 1.4.8
patsy: 0.4.1
dateutil: 2.2
pytz: 2016.7
blosc: None
bottleneck: 1.2.0
tables: 3.3.0
numexpr: 2.6.1
matplotlib: 1.5.3
openpyxl: 2.2.0-b1
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: 1.1.3
pymysql: None
psycopg2: 2.6.2 (dt dec pq3 ext lo64)
jinja2: 2.8
boto: 2.43.0
pandas_datareader: None
```