Sketch script

This script will allow me to see how a spectral line of wavelength range
vary with a stellar parameter.
Accept input parameters and plot it.

The user can run it outside [i]python and, at this time, it is donig a
plot with the fist value of the `values` list.
Plot animation

I could do an animation. It is very rude but it is working. It is not
saving yet because thrown an error.
Uncomment line to save animation.

In order for the animation to work, I had to install mencoder AND
ffmpeg, but I think that was the ffmpeg that made it work.
Show varying parameter and its value.

The script prints the parameter and its value.
Change name of saved animation
Add script to setup.py. Remove .py from script.
Add information about sensi_line script

Inform user how to use it.
Merge pull request #13 from gabraganca/sensitivity_script

Sensitivity script