consoleLogger circular JSON handling (closes #17)

* JSON objects are sent directly to console such that circular objects will be
handled downstream and interactive inspection is possible (e.g., in Web
Browsers)
* Adds regression tests suite.

Signed-off-by: Adrian-Tudor Panescu <adrian@panescu.com>
level printing padding

* Message levels will be padded when printing for symmetry; the lowest printable
level is used as reference.

Signed-off-by: Adrian-Tudor Panescu <adrian@panescu.com>