Update assets.js: init fix, jaws.log functions

Changes:
-- Fix for jaws.init unit testing

-- Added jaws.log.on (default true) for turning logging on and off.

-- Added jaws.log.error, which writes to console.error (if it exists,
use_console is true, and log.on is true) or calls jaws.log with string
"[ERROR]" + argument

-- Added jaws.log.warn, which writes to console.warn (if it exists,
use_console is true, and log.on is true) or calls jaws.log with string
"[WARNING]" + argument

-- Added jaws.log.info, which writes to console.info (if it exists,
use_console is true, and log.on is true) or calls jaws.log with string
"[INFO]" + argument

-- Added jaws.log.debug, which writes to console.debug (if it exists,
use_console is true, and log.on is true) or calls jaws.log with string
"[DEBUG]" + argument

-- All internal testing of function arguments now use the additional
jaws.log functionality