feature: added support for command-line arguments parsing

* Adding support for command-line arguments parsing
* Adding support for multiple directories to the search paths for Lua libraries
* Using Getopt::Long instead of Getopt::Std
* Adding a new test scaffold
* Adding support for specifying the nginx path (this option might be removed in the future)
Your package defaults look wrong to me. We need to preserve the `;;` value in the end of the value. See

http://www.lua.org/manual/5.1/manual.html#pdf-package.path

> Any ";;" in the value of the environment variable is replaced by the default path.