Build cache Interval paremeterized 

Allows users to configure the interval at which the endpoints are refreshed.  Defaults to the current standard of 5.0 and updated documentation for examples.

fixes #155 
We can do that if you want.  I was trying to make it obvious to the end user that didnt know the internal implementation.  When I first read build_interval, it didnt really make sense to me since we are just checking external services for new updates.

If everyone agrees, I will make the change and bring it in.