Pass indexes to QueryHelpers.validator.validate*

- MongoJavaDriver gets indexes from DBCollectionFactory impl
  this allows list of indexes to be generated by an
  backend that is implementation specific to the model
  type

- this will allow a DBCollectionFactory for spindle to
  return indexes without spindle depending on rogue-index

- NOTE: this changes the interface of:
  DBCollectionFactory (new abstract method getIndexes)
  QueryHelpers.QueryValidator (indexes params)
  MongoIndexChecker (validate methods w/o indexes param
    removed, getIndexes removed)
  New trait IndexChecker to make public interface more clear
Merge pull request #96 from slackhappy/rogue-index-dep

Pass indexes to QueryHelpers.validator.validate*