Add links to deb and rpm files to the download page

Hi,

I found that [the Scala 2.10.3 download page](http://www.scala-lang.org/download/2.10.3.html) does not contain links to [deb](http://www.scala-lang.org/files/archive/scala-2.10.3.deb) and [rpm](http://www.scala-lang.org/files/archive/scala-2.10.3.rpm) files which exist themselves.
I guess this PR fixes that!

See the below for the issue relates to this PR:
https://issues.scala-lang.org/browse/SI-7890

Thanks,
Yusuke Kuoka