Update index.js

1 - The first change was made in the function definition, because of name, this method was more easy to debug.
2 - Added a ternary, to verify if level exists, if not exists the default value was "../", who means in that context go one level up.
3 - Added a verification to archive if not exists just one empty string was defined, to use inside of path.resolve.
4 - The "out" variable was defined to be more expressive and to return the path with resolution, the resolution was important to this module to work with different platforms.
Merge pull request #2 from kaiquewdev/patch-1

Improvements