Refactored entities + views + controllers

A rundown of the changes in this pull request:

- Removed Composer lock file from the repository
- Updated source to use PHP 5.4+ `[]` syntax
- Tried to add better inline documentation/comments
- Added a mode to `users` route (mode is `edit` for editing profiles, and can be `add` to add availabilities to schedules - see list below)
- Renamed `Calendar*` entities to `Schedule*`
- Introduced `ScheduleDay` as an intermediate entity between `Schedule` and `ScheduleInterval`
- Removed extra views
- Merged `layout/logged-out` with `layout/layout`

Still on the to-do list:

- Editing profile information (at `/users/:id/profile/edit`)
- Adding availabilities to schedule
- Matching
- Integrating locations (as per `Location` and `UserLocation` entities)