Provide ability to edit blog articles

[camilleryr]

Story

As an article author, I should be able to edit the title and content after it's been published.

Acceptance Criteria

Given an article author wants to edit an existing article
When the author performs a gesture on the article edit affordance (e.g. button or hyperlink)
Then the article form should be populated with that articles values

Given an article author has chosen to edit an existing article
When the author performs a gesture on the article save affordance (e.g. button or hyperlink)
Then the existing article object in the database should be modified with the new values
And the database should be saved to local storage