[Data] Add a method to the 'LocationManager' class to retrieve the name of the groups
[Data] Add a function to load and deserialize a JSON file
[Data] Add a method to the LocationManager to load locations from a JSON object
[Unittests] Uniformize the way files are read/written by the tests
[Utils] Add a function to determine if a path is absolute or not
[Data] Remove the 'ConfigFile' class

The recommended way is now to use a JSON file
Update the version number to 1.3.0
Version 1.3.0