USER STORY: Edit an event

As a user I can edit an event so that I can fix any mistakes or change the information on the event.

Acceptance Criteria

[x] When I click to view an event, then i am given the option to edit the event
[x] When I click 'edit event', then I am able to change the information
[x] When I click 'save changes', then I am notified that the change was successful
[x] Then I am able to see the updated information on the event detail page
[x] If there is an error, then I am notified that there was an issue updating my event
[x] If I change my mind, then I am given the option to cancel my changes