Timestamp methods not working
Consider the following:

```
> df['lifespan'].head()
0    -7 days +13:01:00
1   -26 days +00:01:00
2   -18 days +00:01:00
3    -7 days +13:01:00
4   -42 days +00:01:00
Name: flight_time_lifespan, dtype: timedelta64[ns]
```

```
> df['lifespan'].values[:5]                                                                                                                         
array([ -557940000000000, -2246340000000000, -1555140000000000,
        -557940000000000, -3628740000000000], dtype='timedelta64[ns]')
```

```
> df['lifespan'][0].days
-7
```

But this does not work:

```
> df['lifespan'].apply(lambda x: x.days)
AttributeError: 'numpy.timedelta64' object has no attribute 'days'
```

Nor does this:

```
> df['flight_time_lifespan'].days
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-29-b649e97cca35> in <module>()
----> 1 df['flight_time_lifespan'].days

/Users/josh/anaconda3/envs/py34/lib/python3.4/site-packages/pandas/core/generic.py in __getattr__(self, name)
   1934                 return self[name]
   1935             raise AttributeError("'%s' object has no attribute '%s'" %
-> 1936                                  (type(self).__name__, name))
   1937 
   1938     def __setattr__(self, name, value):

AttributeError: 'Series' object has no attribute 'days'
```

Nor does this:

```
> pd.show_versions()
INSTALLED VERSIONS
------------------
commit: None
python: 3.4.2.final.0
python-bits: 64
OS: Darwin
OS-release: 14.0.0
machine: x86_64
processor: i386
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.15.1
nose: 1.3.4
Cython: 0.21
numpy: 1.9.1
scipy: 0.14.0
statsmodels: 0.5.0
IPython: 2.3.0
sphinx: 1.2.3
patsy: 0.3.0
dateutil: 2.1
pytz: 2014.9
bottleneck: None
tables: 3.1.1
numexpr: 2.3.1
matplotlib: 1.4.2
openpyxl: 1.8.5
xlrd: 0.9.3
xlwt: None
xlsxwriter: 0.5.7
lxml: 3.4.0
bs4: 4.3.2
html5lib: None
httplib2: None
apiclient: None
rpy2: None
sqlalchemy: 0.9.7
pymysql: None
psycopg2: 2.5.4 (dt dec pq3 ext)
```

The only thing that worked was:

```
df['days'] = [x.days for x in df['lifespan']]
```

I have tried restarting things several times without luck.
