* daemon: Handle new request B_MESSAGE_COMMIT_TRANSACTION. It activates
and deactivates given sets of packages. The new packages must be
placed in a directory in the administrative directory. The daemon
moves them to the packages directory and the deactivated packages to
a subdirectory it creates. It also save the old activation state
there.
* Add private BActivationTransaction, describing an activation change
transaction.
* BDaemonClient: Add CommitTransaction(), which sends a given
BActivationTransaction as a B_MESSAGE_COMMIT_TRANSACTION request to
the daemon.
Completely untested yet.
