Back end: Created the Book database table and it's methods. Resolves #35.
Back end: Refactorised string constants. Fixed URL errors. Resolves #63.
Refactorised string constants. Resolves #63.
Back end: Added numerical constants class.
Back end: Fixed chapter connections.  Resolves #60.
Back end: Created the Chapter database table and it's methods. Fixed string constants. Resolves #36, resolves #60, resolves #63.
Back end: Refactorised SQLite database helper classes.
Back end: Fixed book and chapter database insertion. Refactorised SQLite database helpers.
Created the Question database table and methods. Added question connections. Resolves #37, resolves #59.