Implement Settings

[aaronr93]

As the app developer, I want to be able to change things like the current Gfycat username, number of columns in a feed, etc. so that I don't have to make a code change and rebuild each time.

As an end user, I want to be able to change settings.

Feature ideas:

• Selecting current Gfycat user
• Selecting current Imgur user (if applicable)
• Configurations for debugging purposes

Settings storage options:

• Local file storage
• Core Data
• iCloud

Acceptance Criteria

• A settings page is accessible by the user
• On the settings page, the current Gfycat username is displayed and may be modified
• Feeds only show gifs belonging to the Gfycat username specified on the settings page

Non-Functional Requirements

• Best practices for iOS development and User Experience are consulted.
• View development keeps the iMessage Extension in mind.