ePsiLoN d3 experiments

Host vulnerabiltiy exposure visualisation - v0.2

List of changes

1. Using tipsy JQuery library for the vulnerability labels
2. Utilise ordinal scales to represent vulnerability categories (differnet circle radiuses and legend steps)
3. Simple legend added at the bottom of the chart
4. Entry transition implemented

TODO

1. Represent more then one host
2. Get input from nessus file