Research : protocol buffers

### Is your feature request related to a problem? Please describe.

Currently the app uses sends and receives JSON data. While this is fine when we send/receive data to/from the user (as JSON is human readable) the calls to the mentorship backend do not need to be human readable and can be in the binary form.

### Describe the solution you'd like

Research on the possibility of using protocol buffers and write a doc. In your doc include the advantages / disadvantages of protobufs over JSON and vice versa in context with BIT (You do not need to propose an implementation).

### Describe alternatives you've considered

You could also include a comparison with any other standard that you think would be better (eg. flat buffers) ( This would be optional and not required).