New Demo page for 'watch a demo'

Re-working the demo page into the new style, and incorporating the pricing structure as we've had a few bits of feedback suggesting it would help. Still using the current demo video, but the aim is to have this re-recorded and re-cut ASAP

![image](https://cloud.githubusercontent.com/assets/1246990/3456827/703a6502-01f2-11e4-8f29-d6c3d8d0054e.png)