Johnson::Runtime.require doesn't works as expected

[clbustos]

Using require() on a runtime object throws an error. Looking on prelude.js, I solved the problem replacing the iteration on $LOAD_PATH, currently object based, on an array based.

You can see changes on

http://github.com/clbustos/johnson/commit/fc0354b99bc1c9d39393d5d0d995d1a2df4aaf17