Add support for images

[shirsakm]

The ability to add images to a journal entry needs to be added. It's pretty crucial to the user experience.

The main issues to be tackled are,

• Images need to be assigned a unique ID and stored on disk. The unique ID can then be stored with the journal entry.
• The ability / feature to add images needs to be toggleable. It should be set using an environment variable.
• The interface needs to add a place for these pictures to be displayed effectively.