- they where useing date_between instead of date_between_inclusion

^

tidy volunteers complicated with_billable_hours_scope up and add a test for not including billed again hours

use advanced instead of duration, as it is more timezone safe

fix and make tests with Time more explicit and timezone safe

fix format helper test

fix format helper test

remove tz_parse helper

- so that the user can change the selection made on /billing_expenses
- so that the filter respects billeable records, and not billed as it was
  probably by mistake before

- if the query result delivers hour_ids array, query Hours directly by ids
- in case there is no hour_ids in the query result get hours the same way as before

- convert the scope into method, in order to make use of other model methods
- LEFT OUTER JOIN query, in order to be able to get full query features
- add ARRAY_AGG() functions to select, in order to have hour.id and hour.meeting_date
  in an array within the query result
- exclude volunteers who allready have a billing expense in the given period

- use the methods in BillingExpenseSemesterUtils
- shorten and slicken the whole method

- the profile_link helper was delivering a path, but not a link
- renamed profile_link to profile_url_path (not profile_path to not conflict with path helpers)
- created new method profile_link, that creates a real html link of the user with its full name
  - it also checks for current_user policy credentials, edit? or show? and if none of them, it shows
    the users full_name and email as pure text

- at group_assignments/#{group_assignment.id}/last_submitted_hours_and_feedbacks

- Client can be softdeleted when no assignments associated with it.
- Deleted assignments also taken into account.