Add taxalabels div for biplots and update tests
Add taxa labels functionality for biplots

The following functions were added to the javascript file:
    - Callback to respond to the controller in the user interface
    to show or hide the labels with the taxonomic lineages.
    - Scaling of the biplots when they appear on screen
    - Presentation of the labels when for each frame

Minor updates took place in the emperor.css file to reflec the changes
in format.py and in emperor.js.
Add biplots script usage examples and test data

The main script now supports biplots and jackknifed plots.

Test data was added for the new examples that have been added to the
script interface.

This closes #12