Force default "Limit" for getAll functions with numerous results like events

[ferishili]

Currently the function getAll events for example accepts the limit as one of the paramerts, but when no limit is set, it does not apply any limit, meaning it requests to get all events at once via the external api from Opencast. That could result in an unwanted load on the Opencast (specially when it is a production instance) which also might break the instance.

So in order to prevent this there should be either a new wrapper function around getAll() or adjust the default limit and offset in the getAll functions themselves.