Add links to Scala Center website in footer?

[heathermiller]

/Doh, I didn't even think to do this. Thanks @deathmoves for suggesting :)

[SethTisue]

http://www.scala-lang.org/community/ also

[SethTisue]

did this happen in #606?

[Philippus]

this can be closed, was fixed in #545 I think

[SethTisue]

thanks @Philippus for your attention to this and other tickets recently!