calculate and return the emisisons associated with proposed modes of transport

[clemcodes]

Acceptance Criteria:

• takes in parameter distances dictionary
• returns dictionary of emissions

Notes:

• Create a function in db_utils which gets the information about emissions for each transport mode (should be in km but ask Robyn)
• Create a function which takes parameter distances (dictionary)
• call the function in db_utils to get the emissions
• use this to calculate the total emissions for each mode of transport for that journey (should be an int/float, units which should know)
• return of a dictionary which has transport mode for keys and total emissions per transport as the value (float/int)