Named status constants

Less magic numbers
IsOperationSafe returns bool (as is was intended)

IsOperationSafe now returns bool, it returned int previously for debug
purposes. Thanks to this there are now less magic numbers.
Constant fix

The code used the wrong constant (correct value, wrong name)
Added BucketStatus enum

BucketStatus replaces the named status constants
Moved BucketStatus to a separated file
IsOperationSafe new returns bool
QueueBucket now uses BucketStatus
IsOperationSafe now returns bool
Added missing constant references
Reordered IsOperationSafe
Removed unnecessary initialization
Removed unnecessary initialization
comments
SetBucket now uses BucketStatus

SetBucket now uses BucketStatus
Also comments have been updated
Reordered IsOperationSafe
Added missing constant references
Reordered IsOperationSafe