As an admin I can see the list of hashtags so that I can add or remove them

[utunga]

Acceptance criteria

• [x] I can see a list of hashtags on this page
• [x] It is possible to click into a hashtag to edit its properties
• [x] You can see the icon (if any has been assigned) otherwise it shows the default icon but grayed out
• [x] The admin can click something to add a hashtag
• [x] If a hashtag is not being used they can delete that hashtag

Mockups

No mockup is available! Yeesh. Just make something up pretty please.