bzr add: add more verbose message

[jari]

When adding a large directory with ignore patters, the message looks
like:

        ...
        ignored 70 file(s).
        If you wish to add some of these files, please add them by name.

One may wonder what files were ignored, so perhaps the message could also
instruct:

        ...
        ignored 70 file(s). To see those, use command: bzr ignored.
                           ========================================
        If you wish to add some of these files, please add them by name.

Jari