[Issue #36] Adding a function to get the session id before creating a session

This pull request depends on the following issue: https://github.com/SMILEConsortium/smile_teacher_android/issues/36

The teacher app send a JSON request to the url /smile/createsession
Instead of storing the session id ​​in the database, the added function just show this :

## Console.log ##
     JSON from "createSessionFromTeacherApp"
	>>> [object Object]
	>>> Default Teacher
	>>> Session-
	>>> Default Group

We just need to store the values in the database