Adding and Editing Events should be allowed for Admins only

[ahnwarez]

Normal users shouldn't be able to edit or add events.

When you log in as a normal user and navigate to /gardens/:id, the 'Edit Event' link is visible, this link should only be visible to Admins.

Think about how you can hide/show the Edit button based on the isAdmin flag in redux.
Also you consider protecting the client route /events/:id/edit and /event/new