Lua variables for absolute path and relative path

[sh-zam]

We need a variable to know the absolute path of the init.lua file, so we can prepend it to the hard coded values in the lighttouch-base.

This will make accessing them from external directories possible.

One approach can be to do something like https://github.com/foundpatterns/torchbear/blob/master/src/lib.rs#L88

[dariusc93]

Could possibly modify https://github.com/foundpatterns/torchbear/blob/master/src/lib.rs#L172-L175 and have it give the absolute path and pass that path along.