starting spectrum.py
updated files
Merge https://github.com/odarbelaeze/spectraplotpy
imported namespace spectrum in __init__.py
implemented test_construction in the test_spectrum
implemented test_copy in the test_spectrum
Merge branch 'master' of https://github.com/odarbelaeze/spectraplotpy

Conflicts:
	spectraplotpy/__init__.py
implemented mul and add in spectrum.py
modified test_copy and test_add in test_spectrum.py
Merge pull request #4 from ariamania/master

added the operation of a spectrum