Adding trigger to ensure if-unmodified-since.

jdbc-set has been updated with an addition modified to support this.
Upsert with modified WIP.
Ground work for if-unmodified-since support.
Removing the RAISE NOTICE on rejection.
updating jdbc-set
Added ts handling up to the HTTP layer.
++default max pool size
Reformatting to make tests more readable.
Fixing tests.
Adding NOT NULL to *_at cols.

If we want to ensure consistency, the modified_at column can't be null.
Unconditionally accept updates with no ts.

If a PUT/POST is submitted without an If-Unmodified-Since header, the request
will be unconditionally accepted and the modified at of the object will remain
as-is.
Updating README with a note on If-Unmodified-Sinc.
Commenting testing behavior.
Updated rational.
Adding unconditional PUT to http test.
Ensuring UTC. Fixing date handling.

Reference:
http://stackoverflow.com/questions/6151084/which-timestamp-type-to-choose-in-a-postgresql-database
Hrm. How to handle bad dates?
Handle malformed If-Unmodified-Since.

If the If-Unmodified-Since header is present and doesn't parse as an RFC 1123
date format string, the request will be rejected with a 400.
Renaming the additional sql file. Update README.
triggers cleanup