Return type of Canadian EmissionActivityRatio function

[Trevor Barnes]

Most of the functions in our code base return dataframes that we append together. In the EmissionActivityRatio.py, the getCanEmissionActivityRatio() returns a list rather then a dataframe. I think we should change this for consistency sake :)

Canada-U.S.-ElecTrade/scripts/EmissionActivityRatio.py

Lines 24 to 27 in c8af7e6

 def getCanEmissionActivityRatio(): 
     # PURPOSE: Creates EmissionActivityRatio file from Canadian data 
     # INPUT:   N/A 
     # OUTPUT:  dataOut = Canadian Emission Activity Ratio data 

[Kiel-SFU]

This should also be changed for ReserveMargin.py, ResidualCapacity.py, SpecifiedAnnualDemand.py, and SpecifiedDemandProfile.py.