Categories

__Problem:__ When displaying categories in an aside, if you view the aside from within a post. The aside only shows the categories the post was tagged in.

__Solution:__ When Posting to the '/compose' method on the TestModule, 
    1. Set the Categories property of the BaseViewModel to be the Categories property of the TestModule.
    2. Create a new property on the PostViewModel, and set that property to equal the categories the post is tagged in.