[Run2_2017] Update getWeightProducer Code
Created by: aperloff
This PR updates the getWeightProducer code. It splits off the MCSample list into their own python files separated by production era. This will help in maintaining all of the files involved. It also makes it so that other python modules can take advantage of (i.e. import) the MCSample lists.
The new version of the code has been successfully unit tested (test 7).