README.md, lints'n warnings

Changes
------------

* add a more usefull example to README.md of how to use the library (compile a SCSS file)
* fix 3 *method cannot return both with and without value* warnings
* make a few variables final
* shorten return statements
* remove **alot** unused imports

Bug
-----

Build is currently failing because of *cyclic variable* error, will be most likly fixed in my next pull request