Fix get events not returning user events

[ncareau]

The get_events() function from the AuthenticatedUser class doesn't return events of only the user, it returns all events.

I have modified the function to return user events only, with a flag on getting Private and Public events (False, Default), or just Public events (True).

The original functionality is covered by Github.get_events().

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ncareau]

Still an issue.

[hellkite500]

This definitely feels like a bug in the mapping of the python objects to the API, given that there is a /users event end point and a generic, public /events endpoint. I was about to open an issue about this exact issue and found this PR. If an issue would be be useful I'll create one to link to this PR.