This commit adds a query param `ast_only` to the root endpoint that, when
true, will translate the query from PQL to AST, rather than query the database.

This commit adds an inventory endpoint of fact name=>value pairs, along with
capability to query it and the resources parameters column with "dotted syntax"
like [= parameters.foo bar]. Also add support in PQL. This does not include
projection of nested elements.

This commit adds a "producers" query endpoint and includes reports, catalogs,
and factsets as subquery endpoints.

Fixes a regex bug introduced in the switch to comidi, which disallowed colons
in routes (e.g resource types/titles, etc)

This commit fixes our `pretty` parameter for query POSTs, before this
commit we weren't properly passing the param from the POST body to the
produce-streaming-body function and weren't allowing the parameter
through validation.

This commit adds parent checking queries for the new historical-catalogs
child data endpoints in PE.

This patch introduces the new Puppet query language to PuppetDB. It provides a basic
parse for this capability, documentation for the new language and a hook in the
index endpoint for the HTTP API side.

As this work is fairly new and extensive, some of the expected work has been
broken into future tickets. For now, this is marked as experimental until we are
happy with the language.
Signed-off-by: Ken Barber <ken@bob.sh>

This commit changes make-pdb-handler to decode all route-params before
calling any handlers. This commit also changes the name of the basic
handler construction function from `create-handler` to
`create-query-handler` to more clearly communicate it's intent.

Existing moustache handlers each provided param specs that were used to
validing incoming request parameters. With the newly refactored
handlers.clj, most of these can go away. The extract-query function
includes a default which most handlers use.

Added schema checks to the non-query comidi routes (admin, metrics,
meta, dashcoard). Removed some unnecessary bidi ns requires.

All query routes moved from http/v4.clj to http/handlers.clj and are
parameterized by version (currently only v4). This
leaves v4.clj with only the top-level routes (i.e. /facts) and passes the
version into the corresponding routes function (facts-routes) for
handling the nested routes under that segment.