Globalize utility type list
Created by: chenzheng06
!! Previous PR needs to be merged before reviewing this PR
Convert 'electricity' to 'electric'. Replace 'electricity' variables with a global constant UTILITY_TYPE_LIST[0], and other utility types as well. Comment some useless functions, which resulting failure for unit test test_other
unit test for test_scenario is messed up totally, need to re-write. other unit tests are passed, except for the ones that were not working already (like test_other)