upgrade modules to use plugin 2.x

[SethTisue]

PRs

• sbt 1 upgrade scala-parallel-collections#57
• upgrade to sbt 1 scala-java8-compat#134
• upgrade to sbt 1 scala-async#215
• move to sbt 1 and sbt-scala-module 2.x series scala-partest#116
• upgrade to sbt 1 scala-collection-compat#184
• upgrade to sbt 1 scala-parser-combinators#190
• upgrade to sbt 1 scala-swing#93

issues

• upgrade to sbt 1? scala-xml#278

[SethTisue]

scala-xml issue remains open. other repos completed.

[SethTisue]

forgot about scala-continuations before, but it's done now: scala/scala-continuations#47

and scala-xml is done now too, scala/scala-xml#291