Define name of mesure type in its definition, not at registering

[ChillPC]

Instead of having :

    this.measures.register('temperature', temperatureMeasure);

Have simply:

    this.measures.register(temperatureMeasure);

With 'temperature' defined in its file with the mappings and the unit

[Aschen]

Actually the type of the register method is only used to ensure that we don't register twice the same measure, then the type of a measurement should be set inside the decoder:

• https://github.com/kuzzleio/kuzzle-device-manager/blob/2-stable/features/fixtures/application/decoders/DummyTempDecoder.ts#L37
• https://github.com/kuzzleio/kuzzle-device-manager/blob/2-stable/lib/core-classes/MeasureService.ts#L208