Fix and enhancements
* Set line size to 100 chars and cleanup code
* Fix Travis build (remove `django` modules when testing)
* Always install pillow when installing with -e imaging
* Update README to reflect newer options
* Class `multimedia.exif.brand.Brand`: Add more brands
* Class `multimedia.exif.image.Orientation`: Use standard Enum, or object if not available
Features
* Add module `ai`