handleGetCategory: sender.tell corrected
dataset log messages moved to DatasetLog/DatasetLogType
MessageProperties converted into interface
dataset attribute added to DatasetLog
Merge pull request #181 from IDgis/admin-fix

handleGetCategory: sender.tell corrected
java generics compiler issue resolved

Eclipse accepts typecasts beween raw types and wildcard types but javac
doens't.
Merge pull request #182 from IDgis/dataset

Dataset
DatabaseRef -> AsyncDatabaseHelper
AsyncDatabaseHelper improved
various cleanups

Iterable -> TypedIterable
custom timeout -> standard timeout
provider protocol and domain refactored
DatasetManager implementation started