[io] comment option ignored in read_csv when sep provided.
``` python
In [8]: import pandas as pd
In [9]: from StringIO import StringIO
In [10]: s = """#        date,            utc,             jdate, orbit, sundist,   sunlat,    sunlon,             sclk,     sclat,     sclon,       scrad,       scalt,  el_cmd,  az_cmd,   af, orientlat, orientlon, c, det,    vlookx,    vlooky,    vlookz,   radiance,       tb,      clat,      clon,     cemis,   csunzen,   csunazi, cloctime, qca, qge, qmi"16-Apr-2011", "00:00:00.025", 2455667.500000290,  8352, 1.00538,  1.33678,  27.55755, 0324604799.65011, -35.60774, 186.36107,  1798.15230,    60.70145, 180.000, 240.000,  110,   0.42378, 275.92764, 1,   1,  0.790839,  0.052956,  0.609729,     0.0077,    0.022, -35.53812, 186.44733,   2.91887, 140.57684,  10.78604, 22.59250, 000, 012, 000"""

In [11]: s = StringIO(s)
In [12]: columns = ['date', 'utc', 'jdate', 'orbit', 'sundist', 'sunlat', 'sunlon', 'sclk', 'sclat', 'sclon', 'scrad', 'scalt', 'el_cmd', 'az_cmd', 'af', 'orientlat', 'orientlon', 'c', 'det', 'vlookx', 'vlooky', 'vlookz', 'radiance', 'tb', 'clat', 'clon', 'cemis', 'csunzen', 'csunazi', 'cloctime', 'qca', 'qge', 'qmi']
In [13]: pd.io.parsers.read_csv(s,sep='\s+',names=columns,comment='#')
Out[13]: <class 'pandas.core.frame.DataFrame'>Int64Index: 2 entries, 0 to 1
Data columns:date         1  non-null valuesutc          1  non-null valuesjdate        1  non-null values
orbit        1  non-null values
sundist      1  non-null values
sunlat       1  non-null values
sunlon       1  non-null values
sclk         1  non-null values
sclat        1  non-null values
sclon        1  non-null values
scrad        1  non-null values
scalt        1  non-null values
el_cmd       1  non-null values
az_cmd       1  non-null values
af           1  non-null values
orientlat    1  non-null values
orientlon    1  non-null values
c            1  non-null values
det          1  non-null values
vlookx       1  non-null values
vlooky       1  non-null values
vlookz       1  non-null values
radiance     1  non-null values
tb           1  non-null values
clat         1  non-null values
clon         1  non-null values
cemis        1  non-null values
csunzen      1  non-null values
csunazi      1  non-null values
cloctime     1  non-null values
qca          1  non-null values
qge          1  non-null values
qmi          1  non-null values
dtypes: float64(1), object(32)

In [14]: pd.__version__
Out[14]: '0.11.0.dev-b3e696c'
```

expected: 1 entry (comment line should have been ignored)
