BUG: Accept unicode quotechars again in pd.read_csv
Title is self-explanatory.  Affects Python 2.x only.  Closes #14477.

@gfyoung I think there is already `compat.text_type` that does this (capturing unicode/str for py2/py3)
 @jorisvandenbossche : Ah, good catch.  Fixed.
 @jorisvandenbossche : Could you cancel Travis builds <a href="https://travis-ci.org/pandas-dev/pandas/builds/170552837">#170552837</a> and <a href="https://travis-ci.org/pandas-dev/pandas/builds/170586342">#170586342</a>?  Thanks!
 ## [Current coverage](https://codecov.io/gh/pandas-dev/pandas/pull/14492?src=pr) is 85.26% (diff: 100%)

> Merging [#14492](https://codecov.io/gh/pandas-dev/pandas/pull/14492?src=pr) into [master](https://codecov.io/gh/pandas-dev/pandas/branch/master?src=pr) will increase coverage by **<.01%**

``` diff
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  Files           140        140          
  Lines         50670      50672     +2   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
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+ Hits          43205      43207     +2   
  Misses         7465       7465          
  Partials          0          0          
```

> Powered by [Codecov](https://codecov.io?src=pr). Last update [e3d943d...ec9f59a](https://codecov.io/gh/pandas-dev/pandas/compare/e3d943d1876e8914036e9c323f1876e52da34a04...ec9f59a0feb13ae2e1a47aeda3f07eef18b27be9?src=pr)
 @jorisvandenbossche : Also <a href="https://travis-ci.org/pandas-dev/pandas/builds/170586654">#170586654</a> if possible, as I figured out what was causing the 2.7 machine to fail.  The 3.4 failure is unrelated.
 looks fine to me; try with an actual unicode quotechar though, e.g

```
In [1]: "\u0394"
Out[1]: 'Δ'
```
 Actual unicode quotechar do actually fail (see the tests). But I don't think we need to support actual unicode quotechars, just supporting ascii chars that are passed as unicode is enough IMO.
 @jorisvandenbossche : Agreed.  The current failure is because of Python 2.x.  I modified test so that last check is only done on Python 3.x
 lgtm. thanks.
 @gfyoung thanks!
