Fix some bugs, correct natural ordering, slicer test and aggregate and update tests

[ThamaluM]

Correct bug due incorrect call of Workspace module which is imported relatively.

[ThamaluM]

Fixed natural ordering fix bugs in slicer test and slicer aggregate fix tests (remove amount_sum check in test_aggregates and remove depreciation exception at the beginning of the test) Add ArgumentError for unknown function. Fix the problem in metadata/base/localized due to using setattr for a shallow copied object. Add test for python 3.4 to 3.7. Remove 3.3 test (travis server cannot access )

[ThamaluM]

I closed this by accident so I reopen it again.