Fix for Django 1.7

[AlexProfi]

please fix it for Django 1.7

+++ b/cmsplugin_carousel/models.py
@@ -30,7 +30,7 @@ class CarouselPicture(OrderedModel):
     text = models.TextField(verbose_name=_('Text over image'), blank=True)
     url = models.CharField(verbose_name=_('URL'), blank=True, null=True, max_length=500)
     page = PageField(verbose_name=_("Page"), blank=True, null=True)
- open_in_tab = models.BooleanField(verbose_name=_('Open in new window'))
+ open_in_tab = models.BooleanField(verbose_name=_('Open in new window'), default=False)

[AlexProfi]

It will be very good if it can to load many photos by one time