Add module command does not account for capitalisation

[indraneelrp]

Since the module codes in a university are not case-sensitive, a user may tend to enter a module without capitalisation. However, this is not handled by the program.

The program reports that there is no such module, when the user is expecting that there is indeed such a module. However, only the capitalisation is missing

[nus-pe-bot]

Your response not required for this bug as the team has accepted the bug as it is.