Unicode char as delimiter won't use C engine
I have the following code:

`dfEL = pd.read_csv(IN_PATH, delimiter='\\u00A7', encoding='utf-8')`

which I've also tried with other ways of writing the delimiter, e.g.:

`dfEL = pd.read_csv(IN_PATH, delimiter='§', encoding='utf-8')`

These other methods don't work, and generate a `UnicodeDecodeError: 'utf-8' codec can't decode byte 0xc2 in position 10: unexpected end of data`.

The first method, though, won't use the C regex engine:

```
dfEL = pd.read_csv(IN_PATH, delimiter='\\u00A7', encoding='utf-8')
C:\Anaconda3\lib\site-packages\ipykernel\__main__.py:1: ParserWarning: Falling back to the 'python' engine because the 'c' engine does not support regex separators (separators > 1 char and different from '\s+' are interpreted as regex); you can avoid this warning by specifying engine='python'.
  if __name__ == '__main__':
```

Shouldn't this only be considered one character and still use (the I presume faster) C engine?

Sample data - there's a lot of messiness in the rightmost column, which is why an unusual separator was used:

```
foo§1457431587429§$request_details.bar
foo§1457431587429§$request_details.foo.bar
foo§1457431587429§$request_details.foo.foo.bar
foo§1457431587429§null
foo§1457431587429§null
foo§1457431587429§null
foo§1457431587429§$request_type
foo§1457431587429§$additional_details
foo§1457431587429§$Generic_Params.success_msg_folder+$request_type.action+'_'+$request_type.object
§1459972605829§$Path
§1459972605829§$Name
§1441995198746§$original.original
§1441995198746§null
```

```
pd.show_versions()

INSTALLED VERSIONS
------------------
commit: None
python: 3.5.1.final.0
python-bits: 64
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: 1.3.7
pip: 8.1.1
setuptools: 20.3
Cython: 0.23.4
numpy: 1.11.1
scipy: 0.18.0
statsmodels: 0.6.1
xarray: None
IPython: 4.1.2
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: 2.6.1
matplotlib: 1.5.1
openpyxl: 2.3.2
xlrd: 0.9.4
xlwt: 1.0.0
xlsxwriter: 0.8.4
lxml: 3.6.0
bs4: 4.4.1
html5lib: None
httplib2: 0.9.2
apiclient: 1.5.0
sqlalchemy: 1.0.12
pymysql: None
psycopg2: None
jinja2: 2.8
boto: 2.39.0
pandas_datareader: None
```
