Abide verification framework

First internal release of the abide framework that features:
- reflective rule and analyzer loading
- abide compiler plugin
- basic cli that provides 4-phase compilation with abide on top
- sbt plugin sketch (needs version management)
- traversal analyzer that applies single-traversal rules
- scoping analyzer that applies single-traversal rules and provides scoping and/or path information
- a few example rules and doc on how to add more

Yes, by default scalatest seems to run the tests in parallel and I saw no reason to disable it though it doesn't make that much sense since all the heavy work is done inside the ask call. I guess we could change this to make test writing simpler. Should I?