Upgrade scala, sbt and some sbt plugins

[seratch]

This pull request fixes the issues below:

• Upgrading oudated sbt version
  • from 0.13.9 to 0.13.12
  • The Build trait is deprecated since 0.13.12 and will be removed in 1.0 (see also https://github.com/sbt/sbt/releases/tag/v0.13.12, https://github.com/sbt/sbt/pull/2530)
• Upgrading outdated scoverage, coveralls plugin
  • Travis builds sometimes look unstable, I hope this upgrade makes the situation better
  • Upgrading other sbt plugins brings more changes, I'll work on them in another pull requests
• Upgrading Scala patch version
  • from 2.11.7 to 2.11.8
  • Fix release scripts as well

[coveralls]

Coverage decreased (-0.2%) to 82.692% when pulling f1a357dec3ec91f316568644dbbbcd8d2fc9b68a on seratch:bump-sbt-scala into 54791e8f38332dccc1b3d93f51d941cbcc2b1239 on m3dev:develop.

[seratch]

I've upgraded scoverage version to the latest but the tests still occasionally fail on TravisCI although they never fail on my local machine. I reran the job and it succeeded then.

[seratch]

Ah, indeed, I should have saved the outputs... I'll save the failures next time.

[btakashi]

(Ah, perhaps I don't have the authority to approve the request, in the future I'll leave that up to others)