wrong addition between Series of type datetime64 and timedelta when tz is set and different from UTC
It seems there is an issue when adding a timedelta to a Series of type datetime64[ns, some tz]. There seems to be an issue with the offset/DST.
#### Code Sample, a copy-pastable example if possible

```
import pandas

sr = pandas.Series(pandas.DatetimeIndex(["2016-11-03 16:00:00+01:00", "2016-10-25 17:00:00+02:00"]).tz_localize("UTC").tz_convert(tz="Europe/Brussels"))
print(sr)
print(sr + pandas.to_timedelta(0, unit='h'))

```
#### Actual Output

```
0   2016-11-03 16:00:00+01:00
1   2016-10-25 17:00:00+02:00
dtype: datetime64[ns, Europe/Brussels]
0   2016-11-03 16:00:00+01:00
1   2016-10-25 16:00:00+02:00
dtype: datetime64[ns, Europe/Brussels]
```
#### Expected Output

```
0   2016-11-03 16:00:00+01:00
1   2016-10-25 17:00:00+02:00
dtype: datetime64[ns, Europe/Brussels]
0   2016-11-03 16:00:00+01:00
1   2016-10-25 17:00:00+02:00
dtype: datetime64[ns, Europe/Brussels]
```
#### output of `pd.show_versions()`
## INSTALLED VERSIONS

commit: None
python: 3.5.2.final.0
python-bits: 32
OS: Windows
OS-release: 7
machine: AMD64
processor: Intel64 Family 6 Model 61 Stepping 4, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.18.1
nose: None
pip: 8.1.2
setuptools: 23.0.0
Cython: None
numpy: 1.11.0
scipy: 0.17.1
statsmodels: None
xarray: None
IPython: 4.2.0
sphinx: None
patsy: None
dateutil: 2.5.3
pytz: 2016.4
blosc: None
bottleneck: None
tables: None
numexpr: 2.6.1
matplotlib: 1.5.1
openpyxl: 2.3.2
xlrd: 1.0.0
xlwt: None
xlsxwriter: 0.9.2
lxml: 3.6.0
bs4: None
html5lib: None
httplib2: 0.9.2
apiclient: None
sqlalchemy: 1.0.12
pymysql: None
psycopg2: 2.6.2 (dt dec pq3 ext)
jinja2: 2.8
boto: None
pandas_datareader: None
