Plot synthetic spectrum over observed. Set colors.

The synthetic spectrum will overplot the observation spectrum. Close #20

I have also set the default colors. I took the colors from the 'Set1' of
the 'qualitative' set from colorbrewer2.org. The matplotlib colors were
taken using the jiffyclub/brewer2mpl package. I do not use the package
because I did not want to force the user to install it.
Add a version.

I just add 'v1.0-dev', but it will change when I release a stable
version.