[IMP] note: Use first stage as default stage_id if is stage_id empty

UI improvement:
If there is no stage then there will be no button(no status bar) but there will be stages but task or note etc.. will not be in any stage then there will be 'undefined' so by click on that ('undefined') user can move to any stages. To avoid this behavior we add a default stage in note.

addons/note/models/note.py

@@ -45,7 +45,7 @@ class Note(models.Model):
     memo = fields.Html('Note Content')
     sequence = fields.Integer('Sequence')
     stage_id = fields.Many2one('note.stage', compute='_compute_stage_id',
-        inverse='_inverse_stage_id', string='Stage')
+        inverse='_inverse_stage_id', string='Stage', default=_get_default_stage_id)
     stage_ids = fields.Many2many('note.stage', 'note_stage_rel', 'note_id', 'stage_id',
         string='Stages of Users',  default=_get_default_stage_id)
     open = fields.Boolean(string='Active', default=True)
@@ -62,9 +62,13 @@ class Note(models.Model):
 
     @api.multi
     def _compute_stage_id(self):
+        first_user_stage = self.env['note.stage'].search([('user_id', '=', self.env.uid)], limit=1)
         for note in self:
             for stage in note.stage_ids.filtered(lambda stage: stage.user_id == self.env.user):
                 note.stage_id = stage
+            # note without user's stage
+            if not note.stage_id:
+                note.stage_id = first_user_stage
 
     @api.multi
     def _inverse_stage_id(self):