Added python-imaging dep for Fedora 20

In Fedora 19+, python-imaging is supplied by python-pillow
Added joystick dep for Fedora 20

In Fedora 18+, joystick is provided by linuxconsoletools
Added libusb-1.0-dev dep for Fedora 20

In Fedora 19+, libusb1-devel is provided by libusbx-devel
Copied some assimp deps to assimp-dev

Not sure when folks will start migrating to assimp-dev, but if we're not going to distinguish between them, the assimp-dev key should be removed.
Merge pull request #2929 from cottsay/master

Added fedora 20 deps for python-imaging and joystick