dynamically generate tree diagrams

[gregcaporaso]

In Studying Biological Diversity we want to dynamically generate these figures:

which will make them a lot more useful, as we can vary parameter settings and see the effect on the tree. This could be an optional visual output for a unifrac calculation.

In Phylogenetic Reconstruction, there are a lot of trees through-out that are statically generated. Many of which are annotated.
This should be done after the scikit-bio TreeNode refactoring, or alternatively with ete2. It'd be great to start exploring options in an IPython Notebook to recreate these figures.