Support multiple projects/products

[portertech]

The current Sensu docs site includes several Sensu tools in a single "bucket". We need a way to separate documentation on a per-product/product basis. InfluxDB does a fantastic job of this, see: http://docs.influxdata.com/

This issue will likely need to "explode" into several, more technical, github issues.

[portertech]

Some examples of Sensu related projects/products are "Sensu", "Sensu Enterprise", "Uchiwa", "Sensu Enterprise Dashboard", and "Sensu Plugins".

[portertech]

@dabria I really like InfluxDB's tile layout for project/product selection, I now have design tunnel vision! Do you have an alternative layout in mind? It's ok if you don't, I am more than happy to stay in the tunnel.

[dabria]

I honestly love it too, for the time being I am perfectly content in the tunnel. Once I have some more functionality I'll customize the homepage a bit more to have it look similar (with our own special spin on it)

[portertech]