Added a bar chart based on array of data, with gloss disabled

Thanks for the library, found it really useful. Added a more convenient method (IMO) that enables setting up bar charts with NSArray of NSDictionaries (value and label pairs), automatically colouring them with a flat colour palette

Here's a screenshot

![screen shot 2013-07-29 at 12 40 29](https://f.cloud.github.com/assets/993164/871233/103dd23c-f844-11e2-93f6-601dba9cd4e5.png)