Added a tree and buttons to the forms

The first form page will contain a tree/list of RPMs that
the user would want to create a repository for. There will
be commands to handle importing rpms from the file system,
removing rpms from the tree, and executing the createrepo
command.

TODO: add drag and drop functionality from workspace to tree

FIX : margins use magic numbers, find better way to be similar
    to update site form page

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