finalized the average_spectra() method in the plotter_helper.py
finalized the test_average_spectra() in test_plotter_helper.py
Merge branch 'master' of https://github.com/odarbelaeze/spectraplotpy
Merge pull request #24 from ariamania/master

finalized the test and creation of the average_spectra()
Getting rid of the validation function.
Mocking the dependencies.
Merge branch 'master' of https://github.com/odarbelaeze/spectraplotpy