[REFACTOR] moved ActivitySequencer class into project.internal package

This class is more bound to the business logic because of its
heavy usage of activity DAOs. Moved it into the right place where
it should belong to.

Change-Id: I7a1d38fb6e2b33149bcede59db6433bfa7002aa9
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/913
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>