Partial revert of 91db4ff2
Keep parameters when cloning bookings
Small style fixes
Install dev requirements in environment
Merge branch 'v1.2'
Merge branch 'master' into wip/future-db
i18n-related encoding fixes

Fixed double decodings and encodings. Added unicode-safety to _().
Typo in migration_to_sqlalchemy
Add Room.set_attribute_value

Also:
* Add __repr__ for RoomAttributeAssociation
* Rename Room.update_name
Rename Location.getAttributeByName()
Migrate Holiday

* New table holidays
* Holidays stored per location
* Add Alembic revision
* Remove old HolidaysHolder
Update FoundationSync call
Fix room_occupation script
Rename script to room_occupancy
Fix available rooms filter
Remove unused imports
Add qtip on disabled booking buttons
Highlight conflict checkboxes in booking pages
Fix long room/location names in roomselector