Implement filters on time-entries by uuid

[enriquezrene]

As a user, I want to be able to query the existing time-entries per user as follows:

1. If I don't specify any query parameter, all of my time-entries in the current month are returned

GET /time-entries

The following features are available for admin users only, regular users will get a 403 error:
2. It returns all the time-entries in the current month for the user identified by {uuid}

GET /time-entries?user_id={uuid}

3. It returns all the time-entries in the current month for all of the users specified

GET /time-entries?user_id={uuid-1},{uuid-2},{uuid-3},...

4. It returns all the time-entries in the current month for all of the existing users

GET /time-entries?user_id=*