moved stuff to handle account config into it's own file.

also added two methods.
- searchAccountConfigInConfigDB searches in new account.config DB
- searchAccountConfig searches in new and old DB
and also transparently moves old info to new DB.
added account name as search criterion for missing account.config

this also requires us to transmit account.name to checkCredentials
CheckCredentials can now handle change credentials

change credentials (i.e. if accountId is given) will search
and update account config object.
Check credentials is done first after restore (not really for
installed accounts, but it should... maybe we'll need
to add a banner message on missing credentials here, sometime).
discoveryAssistant will now work with new DB only

this also makes parameters for discovery assistant much easier.
Now only accountId is really required. The other ones can be used
to overwrite account config stuff.
oncreateassistant now stores config in new DB
serviceasstant now searches config at start up

So the config object will be there for all assistants that need it.

Alos adjusted discoveryAssistant to reflect this change.
removed unnecessary global
adjusted syncassistant to new storage place

config now is stored in this.client.config not
in this.client.transport.config => this made things easier.