Add color scale generator

This color generator depends on pylab(scipy) and
it's output is a valid python module. 
By default it'll generate 100 values for a 
certain color scale.
Add 2 generated color scales.

RdYlGn (current but wrong scale)
RdYlBu (should be used in the future)
Add optional RdYlBu scale image for the map.
Remove pylab dependency and use generated scales.

Both Project and Investment views imported pylon
for the heatmap color calculation. This calculation
was replaced by a pre generated color scales modules
imported by those views now.

Remove ecofunds.utils.ignore_pylab function and 
module.
Remove (last) matplotlib import.
Add parsed xml and polygon cache to investment map
Remove unused backsettings.py.
Merge pull request #11 from ecofunds/feature/remove_pylab_colors

Feature/remove pylab colors