Initial stab at entering postgresql contrib code.

Has support for full async pgsql queries. Most of the logic
is hidden behind a KORE_PGSQL() macro allowing you to insert
these pgsql calls in your page handlers without blocking the
kore worker while the query is going off.

There is place for improvement here, and perhaps KORE_PGSQL won't
stay as I feel this might overcomplicate things instead of making
them simpler as I thought it would.
Improvements to pgsql contrib code.

Including but not limited to:
- Correctly use PQerrorMessage() in case we cleanup with PQfinish
- If we get a network error, cleanup the connection
- No longer call the page handler from inside kore_pgsql_handle()
  but instead just put it to sleep in case we don't need it.
  This does grow the http_requests list quite a bit with sleeping
  connections and can perhaps be improved later on.
- Allow us to on error return OK from a page handler from inside
  the completetion block for KORE_PGSQL().
- Count the cummulative time for a request to finish instead
  of the latest run time for the handler.
Layout that stuff like a 80 column terminal nerd.
And mark a request as DONE when we get PGRES_COMMAND_OK.
pgsql_conn improvements.

set conn inside kore_pgsql to NULL when we've completed.
if at kore_pgsql_cleanup() time the conn is still there
we'll drain it as per documentation.
Remove pgsql example from here, reset module.conf back to roots
Properly use pg_config --includedirs + move modules to contrib
Add example pgsql module showing how one can use the KORE_PGSQL stuff
Support postgresl under the bsds
Change path to reflect new contrib folder
add cert/