Cross build scalahost-runtime with 2.8 to 2.11

Cross build scalahost-runtime with Scala 2.8.2, 2.9.2, 2.9.3, 2.10.4
and 2.11.0 (the versions against which SBT is compiled).
Update Travis config to cross build scalahost-runtime
Merge pull request #8 from Duhemm/scalahost-crossbuild

Cross build scalahost-runtime with 2.8 to 2.11