Device specific settings deserialized using Gson

[vibhorSrv]

This pull request is part of the work to make it easier to load/parse device specific settings.

• SpecificSetting.java and SpecificSettingSensor.java are two data classes that store devices specific settings
• We used Gson Library to serialize/deserialize Java objects to JSON
• The specific settings objects are serialized and and stored in project directory as .json files
• These .json files are deserialised on runtime to load device specific settings