Update lwjgl and slick dependencies in SBT build

Hi there ! How are you this year ? :)

I'm submitting this PR after fixing this issue on SBT scage plugin : https://github.com/mvallerie/sbt-scage-plugin/issues/2

Old LWJGL repo' is dead (http://adterrasperaspera.com/lwjgl). LWJGL is now published on Maven Central (version 1.9.1, i didn't notice any conflict, but would need more testing). Thanks to this guy : https://github.com/nguillaumin/slick2d-maven/

Moreover, Slick seems to be abandonned. I thought about removing all the Slick stuff but it was too much work for me at the moment. Fortunately, Slick2d is now published in Maven Central (version 1.0.1, wtf ?) : http://b2s-repo.googlecode.com/svn/trunk/mvn-repo. I have no idea if this is working well or not with this version, i compiled and runned some of your examples, didn't get any issue. So i suppose it should be okay....

I removed B2S repo since your repository provides Phys2D dependency.

Anyway, when you'll get some time, would be nice to get rid of those old dependencies. I mean, i don't know about Phys2D, but Slick seems to be harder and harder to maintain / integrate....i would love to help you if you need ^^.

Also, i didn't update the pom.xml because i miss javaws on my system (ArchLinux). Basically you just need to update repositories and dependencies, should be fine.

Thanks in advance :).