0.5.0 new tasks and sbt caching

Introduces new tasks (which share their sbt chache)

• javafmt formats Java files (done automatically on compile for Compile and Test configurations, unless AutomateJavaFormatterPlugin is disabled)
• javafmtAll formats Java files for all configurations (Compile and Test by default)
• javafmtCheck fails if files need reformatting
• javafmtCheckAll fails if files need reformatting in any configuration (Compile and Test by default)

sbt 1.3.x is required.