Migrated .sbt build definition to .scala build definition.
Added sbt-pgp plugin.
Upgraded to scala 2.9.3
Replaced scala actors with futures in a test for dynamic graph.
Changed Build.scala to support cross compilation
Updated Build.scala to support cross compilation with versions 2.9.3 and 2.10.x
Merge pull request #50 from shrikrishnaholla/codereview

Enabling cross-build for scala versions 2.9.3 and 2.10.3
Some cleanup on cross-compilation. Also upping version number.
Fixed warnings from scala 2.10 compilation