Define Database structure and Setup Firebase

[anna0207]

Define a structure of storing raw data and processed data in Firebase, which is also effective for retrieval in real-time. Also consider how dynamic adding and removing new sensor data should be done.

Setup firebase and implement an example structure to be followed by Arduino project and MVC project

Links: https://firebase.google.com/docs/database/

[SuneJepsen]

@anna0207 @Spiderixius ive created multiple database structures to achieve better scalability and extensibility. Please have a look at the code and then I can explained it afterwards.