New video embed menu

We've added a video embed menu that enables you to choose the size of the video player when you add videos into your stories. Videos can be contained, expanded, or full-width spanning the story from left to right.

Other bugs and fixes:

• Fixed strange jump behavior in subject line in the campaign composer
• Fixed issue with the search function to keep refreshing when typing
• Fixed bug causing contact import to fail and show no error message
• Improved story editor error message
• Improved category list display in site using the Lena theme
• Fixed issue causing contact view numbers not to be updated
• Added support for Catalan language
• Fixed theme thumbnails display in the Themes settings page