New features

• Add ValueEnum support for 2.11: compile-time checked value (Int, Long, Short) based enums
• Add Circe integration

Misc details

• Remove most usage of deprecated stuff in macros (enclosingClass is going to be tough)
• Bump scoverage and coveralls
• Improve build definition
• Improve Readme
  • Add Maven version badge. YAY
  • Simplify intro
• Update Travis to run coverage on more projects
• Fix names
• Bump Play to 2.5 for Scala 2.11.x and stay at 2.4 for 2.10.x