Add custom local storages to sdk dbtool

[davehorizen]

To rollback the storage or to check its version for test purposes it is possible to use the dbtools of the SDK. To interact with the dbtools we need to execute the executable file of the tool called (at the time of writing) sidechain-sdk-dbtools-0.3.4. The list of the local storages name is defined in the DbTool java file of the executable file, it contains only the names of the common storages (common to all sidechains) and the Simple App storages. This list can't be changed or updated at runtime. it would be helpful to have the ability to update this list for example providing them as CLI arguments of the application.

[paolocappelletti]

Furthermore: we should update the testing framework to be able to invoke the dbtools with these new additiona parameters, to allow apps to use it in python tests