this service is kind of storage that allows to store passwords
and to retrieve already stored.
A password can be stored for the session period or persistently.
The persistent way is only possible if configuration allows to use storage.
It stores passwords encripted with a super password. An interaction
is used to ask a user for a super password.
To allow such an interaction, an object that implements XInteractionHandler
interface should be provided. For this purpose InteractionHandler
service can be used.
In case no interaction handler is provided all passwords are stored
for the session period. In case an interaction handler is provided, but
the super password interaction does not return super password ( for any reason ),
NoMasterException exception is thrown to let user use
nonpersistent way explicitly.
