Split AbstractArchive from SrcMLFile.
Changed SrcMLArchive to implement the new SrcMLArchive. Added a new AbstractFileMonitor to handle event routing.
Fleshed out implementation of AbstractArchive & AbstractFileMonitor
* Renamed FileSystemSourceFolder to FileSystemFolderMonitor and updated it to implement AbstractArchive.
* Added "LastModifiedArchive" which will be the default archive.
* Updated DataArchive to use the new AbstractArchive