Loffset doesn't work when resampling with count()
The label offset `loffset` has no effect when resampling a Series using `.count()`:

```
>>> import pandas as pd
>>> import numpy as np
>>> rng = pd.date_range('1/1/2012', periods=100, freq='S')
>>> ts = pd.Series(np.ones(len(rng)), index=rng)
>>> ts.resample('10S', loffset='1s').mean()   #Works as expected, labels are offset by 1s
2012-01-01 00:00:01    1.0
2012-01-01 00:00:11    1.0
2012-01-01 00:00:21    1.0
2012-01-01 00:00:31    1.0
2012-01-01 00:00:41    1.0
2012-01-01 00:00:51    1.0
2012-01-01 00:01:01    1.0
2012-01-01 00:01:11    1.0
2012-01-01 00:01:21    1.0
2012-01-01 00:01:31    1.0
Freq: 10S, dtype: float64
>>> ts.resample('10S', loffset='1s').count()   #loffset has no effect
2012-01-01 00:00:00    10
2012-01-01 00:00:10    10
2012-01-01 00:00:20    10
2012-01-01 00:00:30    10
2012-01-01 00:00:40    10
2012-01-01 00:00:50    10
2012-01-01 00:01:00    10
2012-01-01 00:01:10    10
2012-01-01 00:01:20    10
2012-01-01 00:01:30    10
Freq: 10S, dtype: int64
```

```
INSTALLED VERSIONS
------------------
commit: None
python: 2.7.11.final.0
python-bits: 64
OS: Windows
OS-release: 7
machine: AMD64
processor: Intel64 Family 6 Model 42 Stepping 7, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.18.0
nose: 1.3.7
pip: 8.1.1
setuptools: 20.3
Cython: 0.23.4
numpy: 1.10.4
scipy: 0.17.0
statsmodels: 0.6.1
xarray: None
IPython: 4.0.1
sphinx: 1.3.1
patsy: 0.4.0
dateutil: 2.5.1
pytz: 2016.2
blosc: None
bottleneck: 1.0.0
tables: 3.2.2
numexpr: 2.4.4
matplotlib: 1.5.0
openpyxl: 2.2.6
xlrd: 0.9.4
xlwt: 1.0.0
xlsxwriter: 0.7.7
lxml: 3.4.4
bs4: 4.4.1
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: 1.0.9
pymysql: None
psycopg2: None
jinja2: 2.8
boto: 2.38.0
```
