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/1246990/3458409/376db008-0201-11e4-96c1-06d7b953bbe6.png)