(docs) Port recent docs revisions to 1.6.x branch

This commit brings over the relevant changes from commit eb20757, since PuppetDB
1.6 will stay around a while for PE customers. I applied them by hand rather
than cherry-picking, to ensure no 2.1-isms would sneak over.
Merge pull request #1012 from nfagerlund/jul_2014_docs_16x

(docs) Port recent docs revisions to 1.6.x branch
Merge branch '1.6.x' into stable

* 1.6.x:
  (docs) Port recent docs revisions to 1.6.x branch

Conflicts:
	documentation/api/query/v1/resources.markdown
	documentation/api/query/v2/fact-names.markdown
	documentation/api/query/v2/facts.markdown
	documentation/api/query/v2/metrics.markdown
	documentation/api/query/v2/nodes.markdown
	documentation/api/query/v2/operators.markdown
	documentation/api/query/v2/query.markdown
	documentation/api/query/v2/resources.markdown
	documentation/api/query/v3/events.markdown
	documentation/api/query/v3/query.markdown
	documentation/api/wire_format/catalog_format_v1.markdown