Scale network graph nodes by node 'activity' level

[thundergolfer]

Description

We want members who participate more on Github to be bigger. Simple as that. "Activity" or "Participation" can be just the amount of Events associated with the user in the past X days where X could be just 30. Remember a User objects events can be accessed by user.events.

The size of the node shouldn't scale linearly or quadratically or whatever with number of events. Logarithmic scaling is probably more appropriate, tuned to what looks best. ie. something like 100 events twice the size of 10 events which is twice the size of 1 events.

Basic Implementation Direction

This will be implemented in javascript and become a function that sets the size of a D3.js node according to the value of the node's key in the data payload.