Feature #400 - Resize images to fit on page - Additions

Feature #400 - Resize images to fit on page - Additions

*   `migrations.py`
    *   Removed empty line
    *   Added empty line
*   `models.py`
    *   Added `MediaEntry.get_display_media()` helper function
*   `process_media.__init__.py`
    *	Updated `process_media_initial()`
    	*   Renamed `main` => `original`.
	*   Added condition to `medium`, it's only created if the original
	    dimensions exceed the MEDIUM_SIZE dimensions.
*   `media.html`
    *	The image tag is now populated by `MediaEntry.get_display_media()`
*   `util.py`
    *	Added `DISPLAY_IMAGE_FETCHING_ORDER`, used by `MediaEntry.get_display_media()`