Merge pull request #13 from samskivert/master

Usability improvement and compatibility with SBT 0.11.3.
Modified plugins for SBT 0.12
Remove commented line
Merge pull request #14 from ripla/master

Modify scripted plugin to be able to compile for SBT 0.12
Run a compile and a (copy of) package-war before gwt-devmode.
Show deprecation warnings.
Fixed some deprecated usages.