DATASOLR-196 - Introduce connect() and notOperator() to Criteria.

connect() allows to explicitly create bracketing.
  //z:roo AND (x:foo OR y:bar)
  where(“z”).is(“roo”).connect().and(where(“x”).is(“foo”).or(“y”).is(“bar”))

notOpereator allows to wrap whole or expression parts inside a negating statement
  //z:roo OR -(x:foo OR y:bar)
  where("z").is("roo").connect().or(where("x").is("foo").or("y").is("bar").notOperator())