Implemented course loading together with parallels.
Missing requires.
Removed duplicate columns in parallels table.
Implemented updating of already existing parallels.
Refactored TimetableSlot loading from KOSapi.
Implemented TimetableSlot updating.
Fixed semester code loading.
Renamed column type to parallel_type.
Fixed parallel type loading.
Dropped courses code column (already stored as ID).
Missing requires. Also bundle update.
Added pg_array named scope for parallel teachers.
Implemented simple pagination when loading records from KOSapi.
Added Sequel timestamps extension.
Added more columns to events table.
Implemented simple Room caching mechanism.
Implemented UpdatedParallelsFinder for changed KOSapi parallels lookup.
Added VCR for integration test speedup.
UpdatedParallelsFinder now checks TimetableSlot updated date as well.
Implemented simple UpdateLog in DB.