Change split function so it also returns empty fields; add API access control; support returning http status codes; changes towards support for running as uhttp embedded lua module.
Add simple unit test framework and various other improvements/changes:
* Move logger.lua;
* update quotation style in several files;
* add proposed configuration key layout to conf_defaults.lua;
* move dump function to utils.lua;
* implement (very) basic unit testing environment;
* fix bugs in various functions in utils.lua;
* checkin of preliminary REST API test code.