Change Scala license to unmodified 3-clause BSD.

No longer using the slightly reworded 3-clause BSD license.
This does not change the meaning of the license,
just aligns it with the standard wording.

This was approved by the Scala meeting this week.
    
Added line for Typesafe's copyright, starting in 2011.

All maven metadata for Scala out there points to http://www.scala-lang.org/downloads/license.html, 
so we should redirect that url to license.html. 
Not sure how to do that, but I at least added a line to the redirect notes :-)

See also: scala/scala#2881

review by @sjrd or @heathermiller