project-wide change of copyright, package names, and maven groupIds

copyright: Andy Dennie -> Fizz Buzz LLC
java package names: com.andydennie.* -> com.fizzbuzz.*
maven groupId: com.andydennie.vroom -> com.fizz-buzz.vroom
copyright changes
added Contributing.md file
Update CONTRIBUTING.md
Added rewriteAll() function to force migration on all entities
shorter method to save all entities
Add RewriteAll() method and Migration resource
removed return type from postResource().
Merge branch 'all-entity-migration' of https://github.com/mogupta/vroom into all-entity-migration