Added execution functionality, changed import page

Execution acts similar to how RPM executes its commands, and
will have to see if anything can be changed or improved upon
(most of it was to test if things work).

TODO: have to implement different way to call execute, so that
    options can be taken from the Createrepo page and used for
    execution.
    o will also need to implement the execute function on the
    button available on both Import and Createrepo pages.

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