Update to SBT 0.12.1

We need this to cross-build for Scala 2.9 and 2.10 at the same time.

Signed-off-by: Aki Saarinen <aki.saarinen@valotrading.com>
Upgrade to Scala 2.10 and cross-build for 2.9.2

Signed-off-by: Aki Saarinen <aki.saarinen@valotrading.com>