BUG: fix handling of color argument for variety of plotting functions
parallel_coordinates
- fix reordering of class column (from set) causing possible color/class
  mismatch
- deprecated use of argument colors in favor of color

radviz
- fix reordering of class column (from set) causing possible color/class
  mismatch
- added explicit color keyword argument (avoids multiple values 'color' being
  passed to plotting method)

andrews_curves
- added explicit color keyword argument (avoids multiple values 'color' being
  passed to plotting method)

To recreate the bug:

``` python

import pandas as pd
from pandas.tools.plotting import parallel_coordinates, radviz, andrews_curves

x = pd.DataFrame([[1,2,3,'b'],
                  [2,2,1,'g'],
                  [3,3,1,'r']], columns=[0,1,2,'name'])

parallel_coordinates(x, 'name', colors=['b','g','r'])

# TypeError from scatter
radviz(x, 'name', color=['b','g','r'])

# TypeError from plot
andrews_curves(x, 'name', color=['b','g','r'])

```

parallel_coordinates before:
![ppl_old](https://cloud.githubusercontent.com/assets/3686522/2791463/28c84c9a-cbc7-11e3-9099-9e064d31e995.png)

parallel_coordinates after:
![ppl_new](https://cloud.githubusercontent.com/assets/3686522/2791462/28c73e0e-cbc7-11e3-804e-73dc43cbd6ca.png)

Thanks for the PR. I had those couple comments inline. Could you also add the note you have in `doc/source/release.rst` to `v0.14` under the API section. And you can add a note to the bug section about the other bugs you fixed.

Does this close a particular Github issue?

I'll add this deprecation to https://github.com/pydata/pandas/issues/6581 when we merge.
 Also it doesn't look like Travis ran. You may need to hook it up to your Github account: http://about.travis-ci.org/docs/user/getting-started/ You should just have to sign in.
 I made the changes you suggested.

A Travis build seemed to get launched once I pushed my commit but there we errors that seem unrelated to my changes. Do you have any suggestions on what might be the issue? Here is the build https://travis-ci.org/anomrake/pandas/builds/24206970
 pls rebase to master. travis made some changes over the last couple of days, all fixed now.

travis will automatically build on each commit.
 I tried to rebase but I'm new to this and I'm a bit surprised to see these other commits show up. Any help would be great.
 see here: https://github.com/pydata/pandas/wiki/Using-Git

```
git rebase -i origin/master
```

then

```
git push yourfork yourbranch -f
```
 Looks to have worked now. Thanks for the help.

Also, as far as I know, there was no Github issue for the bugs. 
 I made the change you requested
 If you could rebase one last time and change those `irows` to `icols`, I'll get this merged. Thanks.
 OK done
 Great, thanks!
