QPID-5807: Remove boost::program_options as a header file dependency of qpid/Options.h
- The intent here is to remove the necessity for things using qpid::Options to
  need to link boost::program_options directly.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1602021 13f79535-47bb-0310-9956-ffa450edef68
QPID-5721: Improve exception message used when String operand cannot be interpreted as JSON

* Also made AVC consistently return unmodifiable when converting from a JSON string

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1602078 13f79535-47bb-0310-9956-ffa450edef68