add license and copyright header where missing

@pavoljuhas:  added missing copyright and license info for everything in srfit.  All the old style, so it's all standardized.  Take a look at the last three… _abc.py, _ordereddict.py, and observable.py.  These are pulled from elsewhere and modified.  What to do with those three are sticky.  May need to check legal to see if diffpy header needed (I think it is), as well as checking other information according with original file's license and copyright.