resampling from Day to BusinessDay pulls weekend data back to friday.
#### Code Sample

```python
result = pd.Series(1., pd.date_range('20170101','20181231',freq='D')).resample('B').last().to_period()

print result.index[0]
# Period('2016-12-30', 'B')

pd.Period('20170101', freq='B')
# Period('2017-01-02', 'B')
```
#### Problem description
when i have daily data that spans weekends (e.g., 1/1/2017 which is a Sunday) and try to get the last available value for a BusinessDay, the data falls back to the Friday period.  This is inconsistent with the timestamp of Sunday belonging to the Monday BusinessDay period (e.g., `pd.Period('20170101', 'B')` goes to 1/2/2017). 

#### Expected Output
I would expect that the `result.index[0]` above would return `Period('2017-01-02', 'B')`
#### Output of ``pd.show_versions()``

<details>
INSTALLED VERSIONS
------------------
commit: None
python: 2.7.12.final.0
python-bits: 64
OS: Linux
OS-release: 4.4.0-36-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: None.None

pandas: 0.19.2
nose: 1.3.7
pip: 9.0.1
setuptools: 34.3.0
Cython: 0.24
numpy: 1.12.0
scipy: 0.18.1
statsmodels: 0.6.1
xarray: 0.9.1
IPython: 4.1.1
sphinx: None
patsy: 0.4.1
dateutil: 2.6.0
pytz: 2016.10
blosc: None
bottleneck: 1.2.0
tables: None
numexpr: 2.5
matplotlib: 1.5.1
openpyxl: 2.3.3
xlrd: 0.9.4
xlwt: 1.0.0
xlsxwriter: None
lxml: 3.5.0
bs4: 4.5.1
html5lib: None
httplib2: 0.9.2
apiclient: None
sqlalchemy: 1.0.12
pymysql: None
psycopg2: None
jinja2: 2.8
boto: 2.45.0
pandas_datareader: None

</details>
