Update to scala 2.11

Update factorie to use Scala 2.11.

Only a few changes had to be made:

- In the hcoref package, there was some code that was using "spawn" to do parallel stuff that has now been removed and I replaced with "future"
- Lack of 2.11 support means we have to turn off incremental compilation in the maven plugin, which shouldn't matter since we all use IDE's
- A couple of covariant traits (ElementType and ThisType) that Scala 2.10 had unsoundness bugs with that which don't understand, that I had to add the "@uncheckedVariance" annotation to (see this Scala mailing list post: https://groups.google.com/forum/#!topic/scala-user/5TM08PYHHkk)
- Had to remove some default arguments on overloaded methods since that's not allowed and 2.10 wasn't catching it
- New 2.11 compiler caught a bug in Logger that was referring to an uninitialized integer (always has value 0)
- ConcurrentMap is now concurrent.Map