Refine managed sources for source file tasks

Append to rather than replace managedSourceDirectories and managedSources.
Merge pull request #10 from pvlugter/managed-sources

Refine managed sources for source file tasks
Update dependencies
Release 1.0.0-RC2
Preparing for next development release
Release 1.0.0-RC3
Preparing for next development release
Release 1.0.0
Preparing for next development release
Applied sync incremental code from sbt 1.0.1 - greatly simplifies code.
Merge pull request #11 from sbt/sync-incremental

Applied sync incremental code from sbt 1.0.1 - greatly simplifies code.