Create a Tag

[joshdbarton]

As an admin I would like to be able to create a new Tag so that I can give authors the ability to better classify their posts.

Given an admin is on the Tag list page
When they select the Create Tag button
Then they should be directed to a form in which they can enter a new Tag name

Given an admin has entered a Tag name
When they click the Save button
Then a new Tag should be saved to the database
And the admin should be directed to the Tag list page

NOTE: For the time being it is acceptable to treat all users as admin users. There is a future story about enforcing user permissions.