[Logs] Add a new log listener to output messages to the console

Fix #3
[Data] Add the class 'Athena::Data::LocationManager'

Fix #1
Prettyfying
[Dependencies] Add rapidjson 0.11
Prettifying again
[Data] Add a function to serialize a Describable into a JSON string
[Data] Add a function to serialize a Describable into a rapidjson object
[Data] Add a function to deserialize a Variant from a rapidjson value
[Data] Add a function to deserialize a Describable object from a rapidjson value
[Data] Add a function to deserialize a Describable object from a JSON string
[Dependencies] Update rapidjson to get rid of an annoying warning when using GCC
Update the version number to 1.2.0
Version 1.2.0