Add Longitude gtest (rebase of #601) (#3182)

* Created gtest for Longitude class

* Remove old Longitude test

* Fix syntax for Longitude Tests

* Remove comment

* Revert "Remove old Longitude test"

This reverts commit 608d3fd5c32d7e4a1de7fec407697a0147fbfae0.

* Cleaned file, organzied test cases

* Fixed failing copy constructor test