bug in pandas.read_fwf
line 2549 of parsers.py should be

``` python
self.delimiter = b'\r\n' + bytes(delimiter, 'utf8') if delimiter else b'\n\r\t '
```

instead of 

``` python
self.delimiter = '\r\n' + delimiter if delimiter else '\n\r\t '
```

otherwise an exception is going to be raised on line 2605 of the same module, as it expects `delimiter` to be `bytes` not `str`
#### output of `pd.show_versions()`
## INSTALLED VERSIONS

commit: None
python: 3.5.1.final.0
python-bits: 64
OS: Linux
OS-release: 4.2.0-12-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: pt_BR.UTF-8

pandas: 0.18.1
nose: 1.2.1
pip: 8.1.2
setuptools: 22.0.5
Cython: 0.24
numpy: 1.11.0
scipy: 0.17.1
statsmodels: 0.6.1
xarray: 0.7.2
IPython: 4.2.0
sphinx: 1.3.5
patsy: 0.4.1
dateutil: 2.5.3
pytz: 2016.4
blosc: None
bottleneck: None
tables: None
numexpr: None
matplotlib: 1.5.1
openpyxl: None
xlrd: 0.9.4
xlwt: None
xlsxwriter: 0.7.3
lxml: None
bs4: 4.4.1
html5lib: 0.999
httplib2: 0.9.1
apiclient: None
sqlalchemy: 1.0.13
pymysql: 0.7.2.None
psycopg2: 2.6.1 (dt dec pq3 ext lo64)
jinja2: 2.8
boto: 2.40.0
pandas_datareader: None
