Service Config Tool - Don't prompt user to save changes if no changes have been made

[DavidWiseman]

The user might be prompted to save changes if the newly serialized object is different from the one on the disk. This might occur if a new property is introduced. It could also just be a minor formatting difference that doesn't impact the object.

Instead of setting the original json to the value on disk, deserialize the object and store the re-serialized version of the object before any user changes have been made. The user will only be prompted to save changes if the object has been changed.