Scalastyle linting in admin submodule and travis-ci suggestion.

Fixed a lint error in the last version-up commit.

And I would suggest using not only `sbt test`, but also `sbt scalastyle` in travis-ci to check each commit's lint errors before merging it.

Now, there're too many lint errors in beyond core, so when they're cleared, we can start a work to check scalastyle in travis-ci, I think.