Issue with read_csv and string variables starting with (unclosed) quotes
I seem to have trouble importing strings from a csv file.

```
from pandas import *
from StringIO import StringIO
```
# ---

This works:

``` python
file = StringIO("""\
label1,label2,label3
index1,a,c,e
index2,b,d,f
""")
a0=read_csv(file)
```

```
       label1 label2 label3
index1      a      c      e
index2      b      d      f
```
# ---

But this does not work (with a double quote in front of one of the values):

``` python
file = StringIO("""\
label1,label2,label3
index1,"a,c,e
index2,b,d,f
""")
a1=read_csv(file)
```

```
Error: newline inside string
```

However the following two cases do work (double quote not in front, or closing double quote):
# ---

``` python
file = StringIO("""\
label1,label2,label3
index1,a",c,e
index2,b,d,f
""")
a2=read_csv(file)
```

```
       label1 label2 label3
index1     a"      c      e
index2      b      d      f
```
# ---

``` python
file = StringIO("""\
label1,label2,label3
index1,"a",c,e
index2,b,d,f
""")
a3=read_csv(file)
```

```
       label1 label2 label3
index1      a      c      e
index2      b      d      f
```

This is the case both with 0.8.0 and 0.7.3.

A quick look at the code hints that the issue stems from the fact that the parser, `csv.reader`, is given the 'excel' dialect. Maybe it would be worth considering exposing the dialect specification to the user?
