Switching repository admin and dependent classes to RepositoryRegistry
RepositoryRegistry is used for indexing context now. There is still more work to do
to move the maven dependent parts into its own projects and update the dependencies.
Combining the indexer api and repository api into archiva-repository-api
They have bidirectional dependencies so they are put together in one module.
Adding new classes for a generalized indexer api that will be used for interfaces
and implementation independent tasks.
Reverting the schedule definition back to cron string
Considered it too complex to convert the cron expressions into java interface
that takes all features into account that are possible by quartz cron strings.