Revert "Merge pull request #59 from huitseeker/pr-scala-resolver"

This reverts commit 1c313796ff14c756135912c671dd013ad7d552b1, reversing
changes made to 5aa00b1d8999f553c276f5e830fecf9831d0ee03.
Revert "Merge pull request #58 from huitseeker/update-sbt-0.13.6"

This reverts commit 5aa00b1d8999f553c276f5e830fecf9831d0ee03, reversing
changes made to 9037d7359cdc06b5de77a245ca5c581f74016039.
bump sbt versions to 0.13.5