Remove a Tag from a Post

[hannahhall]

As an author I would like to be able to unassociate one or more Tags from one of my Posts so that I can correct a mistakenly added Tag.

Given the author is viewing Post details
When they select the Manage Tags option
Then they should be presented with a selection of Tags options that are associated with the Post

Given the author has selected the Tags they wish to remove from a Post
When they click the Save button
Then the association should be removed from the database
And the user should be directed to the Post details page
And the removed Tags should no longer be displayed on the Post details page