WIP: add general docs for paging TODO
Remove clojureql references

* The `node` query namespace had a reference to clojureql even
  though it wasn't actually using it; removed.

* The `facts` query namespace had a few functions that were
  implemented using clojureql.  These implementations were
  going to make it harder to implement paging support for
  this endpoint, and the raw SQL implementations are not really
  any more complex; this commit refactors the namespace to
  remove the clojureql references and replace them with raw SQL.
Add basic paging support to `fact_names` endpoint
Add paging support to facts endpoint