Graphity: comments to status updates should be supported

[renepickhardt]

This is somwhwat related to #3 Once someone creates a status update other people have to have the chance to comment on the update. there are several design decisions one has to take into consideration.

• will the comments be a list?
• Will it be possible to vote comments up and down?
• Will the comments form a tree? e.g. comments of comment.
• Will the comment have 2 owners? e.g. the comment / status update before AND the user who posted it.
  • which ego networks will be updated if a comment is added?