Update MiMa to SBT 0.13.0 and Scala 2.10.2

 - Updates Specs dependency, and explicitly includes Mockito and JUnit
 - Updates tests for changes in scalac (no more ScalaObject, and case
   class copy methods for abstract case classes.)
 - Depends on scala-actors. We should update this. Or, see if the GUI is
   actually used and think about deprecating it.
 - Accounts for removed methods from the stdlib and inference changes
   due to the addition of Option.flatten.
 - Update to SBT 0.13.0. The build has not been refactored to take advantage
   of this yet.
Updates to the latest Specs2.
Remove duplicate resolver (it is now standard in SBT.)
Turn on compiler warnings and address them.

Mostly deprecations.
Address (most) warnings in functional tests.

One remains:

    % find reporter/functional-tests -name '*.class' | grep target | xargs rm && sbt ';test-functional;last-grep warn'
    [success] Total time: 34 s, completed Sep 2, 2013 11:13:59 AM
    [warn] /Users/jason/code/migration-manager/reporter/functional-tests/src/test/class-bridge-method-ok/v2/A.scala:7: class bridge in package annotation is deprecated: Reconsider whether using this annotation will accomplish anything
    [warn]   @bridge def foo: Int = (foo: Object).asInstanceOf[Int]
    [warn]               ^
    [warn] one warning found

Incidentally, running `sbt 'clean;test-functional'` *doesn't* seem to
clean the products of compiling the functional tests.
Merge pull request #45 from retronym/topic/sbt-13

Update MiMa to SBT 0.13.0 and Scala 2.10.2