Colours

Chooses a random starting background and foreground and then piggy-backs the #character_for_iteration method to provide "gradient". Can be psychedelic, multiple runs recommended.

![-dqt3baze_igvhocbvxtmwsnl6u-ld9qdcllqqcvlr8](https://cloud.githubusercontent.com/assets/282423/3650051/79717d7e-1118-11e4-9c5b-f42f2548ccf2.png)