added thresholded colorbar

attemps to adress #231

Here is an example for threshold=5 of what it currently looks like:

![bildschirmfoto 2014-11-25 um 18 53 21](https://cloud.githubusercontent.com/assets/3907396/5191981/85c179e6-74f3-11e4-8def-b032366a3684.png)

Greetings from Berlin
Looks like we mostly do this in tests:

11:07:50-admin/git/nilearn (mask_time)$ git grep -ni "import pylab as pl"

nilearn/plotting/img_plotting.py:24:    *import pylab as pl*

nilearn/plotting/slicers.py:16:    *import pylab as pl*

nilearn/plotting/tests/test_cm.py:11:    *import pylab as pl*

nilearn/plotting/tests/test_cm.py:22:    *import pylab as pl*

nilearn/plotting/tests/test_cm.py:29:    *import pylab as pl*

nilearn/plotting/tests/test_img_plotting.py:14:    *import pylab as pl*

nilearn/plotting/tests/test_img_plotting.py:49:    *import pylab as pl*

nilearn/plotting/tests/test_img_plotting.py:62:    *import pylab as pl*

nilearn/plotting/tests/test_img_plotting.py:97:    *import pylab as pl*

nilearn/plotting/tests/test_img_plotting.py:114:    *import pylab as pl*

nilearn/plotting/tests/test_slicers.py:10:    *import pylab as pl*

nilearn/plotting/tests/test_slicers.py:24:    *import pylab as pl*

nilearn/plotting/tests/test_slicers.py:36:    *import pylab as pl*

plot_demo_plotting.py:86:*import pylab as pl*

plot_haxby_simple.py:82:*import pylab as pl*t

plot_ica_resting_state.py:53:*import pylab as pl*t

2014-11-27 11:31 GMT+01:00 Danilo Bzdok <danilobzdok@gmail.com>:

> good idea!
>
> 2014-11-27 11:30 GMT+01:00 Loïc Estève <notifications@github.com>:
>
>> In nilearn/plotting/slicers.py:
>>
>> > @@ -14,7 +14,8 @@
>> >
>> >  try:
>> >      import pylab as pl
>> > -    from matplotlib import transforms
>> > +    from matplotlib import transforms, cm as _cm
>>
>> Agreed but we still have import pylab as pl in a few places. Should
>> probably be fixed in a separate PR.
>>
>> —
>> Reply to this email directly or view it on GitHub
>> <https://github.com/nilearn/nilearn/pull/296/files#r20988283>.
>>
>
>
>
> --
> Viele Grüße,
> Danilo
>



-- 
Viele Grüße,
Danilo