QPID-4624: Implement IN operator for C++ broker selectors
- Implemented parser for IN operator
- Implement In operator evaluator and unit tests
- Syntax is a bit wider than the spec allowing full expressions
  in the contents of the IN expression not just strings.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1457998 13f79535-47bb-0310-9956-ffa450edef68