read_csv(parse_dates=True) failure
from [stackoverflow](http://stackoverflow.com/questions/12138126/difference-between-parse-date-0-and-parse-date-true-in-pandas-read-csv)

``` python
import pandas as pd
from StringIO import StringIO

data = "date,c1\n2012-07-31 02:00,1.1\n2012-07-31 02:15,2.2\n2012-07-31 02:30,3.3\n"

df1 = pd.read_csv(StringIO(data),parse_dates=True).set_index(('date'))
df2 = pd.read_csv(StringIO(data),parse_dates=[0] ).set_index(('date'))

print "df1:\n{index}".format(index=df1.index)
print "df2:\n{index}".format(index=df2.index)
```

df1 has a index of dtype object.
