Section of debugging continuous aggregate issues

[mfreed]

When users encounter issues related to creating caggs or having them properly update we often see that it's attributed to a set of common reasons. We should add a section around "best practices" or "what to check if your caggs aren't working" to the docs.

We'll eventually post below a draft outline for this section; posting as a github issue so that the community could offer their own suggestions before we finalize the docs pages.

[LloydAlbin]

I have found that the continuous aggregate's won't start updating until after you perform a REFRESH MATERIALIZED VIEW and then they will stay up to date. This is an issue for people who are using the Travis CI or Jenkins to perform unit testing of their databases. Whats more, I must specify each continuous aggregate manually due to the fact that PostgreSQL does not support REFRESH MATERIALIZED VIEW inside of a function. If it did then a function could be written to loop through all of the continuous aggregate's in the database and refresh them.