Finish loading spectrum on a full pythonic way.

I have loaded two spectra in a full pythonic way.
One is the original e the other is a cutted and normalized one.

I guess that the functions are ready to be pushed to S4.
Add spectrum in ascii format to test.
Write functions that converts FITS spectrum to a ndarray.

I have created a Intpu/Outpu module. I guess that the JSON class
on utils module should alos be transfered to here. I should write
and issue for this.