Updates to PyData site for multi-events

Added conference to filter for event selection

Prefixed dropdown fields with conference name

Appears to now show different tracks in schedule properly

![screen shot 2013-06-15 at 8 54 55 am](https://f.cloud.github.com/assets/293525/657850/df6b70b6-d592-11e2-8e8a-8fa798a64ed2.png)