added section on configuring jasp. there is still work to be done.
contains a class function decorator to memoize jasp functions.
added a brief alternative idea
I factored out read_spinpol so that every function call in read_outcar could be memoized.

I also monkey patched all the read functions in read_outcar with
memoized versions of those functions.

the get forces, energy and stress functions are not monkey patched. I am
pretty sure they do not read the outcar and there would be no gain in
memoizing them because they just return attributes.