Like Spike Insight

Hi,

As we discussed here is the Like Spike insight, highlighting videos with all time highs and peaks over the average for 30 / 90 / 365 days.

![screenshot from 2013-08-26 18 19 02](https://f.cloud.github.com/assets/851569/1027584/000b412e-0e74-11e3-8855-bcedd11c009c.png)
![screenshot from 2013-08-26 18 18 53](https://f.cloud.github.com/assets/851569/1027583/000708d4-0e74-11e3-9214-7d4358b1d904.png)

It also adds a method to convert numerical multipliers to a string as per the insight guidelines and also includes methods to generate the hot videos charts for any attribute.