Added toolbar button for editor & reviewed project

Made the createrepo project to initialize the project preferences if
not initialized. This will update it to make sure that the RPMs in the
preferences still exist within the project. Modifying the project
outside of eclipse will also update the preferences on opening the
project. The createrepo project also has some common functionality
frequently used from import page that could also be used in other pages.

The button on the repo metadata editor now works the same way as the
button in the import page.

Removed the initialization of the preferences from the project creator.

Signed-off-by: Neil Guzman <nguzman@redhat.com>