Investigate using a proper testing framework

[Leonardo2718]

Currently, test cases are simple Lua scripts that exercise the code paths being tested. This is a less than ideal approach as there is no convenient way of reporting errors. Using a proper testing framework would help organize and cleanup the test cases.

[leejingbo]

The busted is a Lua unit testing framework.

@Leonardo2718 How about using busted for lua-vermelha testing?