change maven groupId from com.squareup to com.fizzbuzz
remove module DoubleCheckedLocking (no longer supported as of Checkstyle 5.6)
add .checkstyle file (generated by Eclipse checkstyle plugin)
add base interface OttoBus, have Bus implement it.
provide more detailed explanatory message with IllegalArgumentException
thrown when conflicting Producer methods are detected.
Merge branch 'add-dot-checkstyle-to-gitignore'
Merge branch 'base-interface'
Merge branch 'remove-checkstyle-doublechecked-locking'
Merge branch 'better-conflicting-producer-exception'