[IMP] initialized room booking schema
[IMP] defined more properties of schema
[FIX] small fixes to make it to run
[IMP] Future-db initial complete room booking schema

- separated tables contain info about multiple entities
- renamed trait to attribute
- added generator for schema graph
[IMP] completed room booking module schema

- fixed principal misunderstanding
- removed separated ids from tables where unnecessary
- better naming and typo fix
[IMP] initial review refactorings

- nullable, default for columns
- argparse instead optparse
- normal import instead of hack
- repr
[IMP] small refactorings (post-wip)

- auto import
- aspect name non-nullable
- pep8
[IMP] removed redundant flag for cascades

- separated content into big and small for photos
- defined missing attributes for columns (nullable and defaults)
[MIN] license in a file, newline at the end of file
[MIN] typo fix, end of line
[REF] Flask-SQLAlchemy integration
[IMP] updated db creator for flask-sqlalchemy
[MIN] license and no newline in bin/utils
[MIN] removed schema package
[MIN] renamed edits -> reservation_edit_logs
[IMP] attribute keys are put into separate tables
[MIN] renamed notification related columns
[FIX] ambiguity between multiple foreign keys
[FIX] mapping into wrong table
[IMP] some utility methods for models