Adds jedi-mode to list of unsupported modes.

jedi-mode is from jedi.el and complements auto-complete-mode by
beginning its internal auto-complete function once the dot key is
pressed (if this feature is enabled). However, multiple-cursors.el
disables auto-complete-mode once it is started. Pressing the dot key
with multiple cursors causes jedi.el to attempt to call a function from
auto-complete-mode, which is now no longer available. This results in a
dot being written to the first cursor, but no other cursors receiving
the dot.

Because jedi.el's jedi-mode only other function is to allow users to go
to variable and function definitions via key commands, it would seem
that none of jedi.el's jedi-mode functionality is really applicable to
multiple-cursors.el. So, this commit adds jedi-mode to the list of
unsupported modes, which fixes the problem of calling complete-on-dot
when the dot key is pressed.