More support for YAML-CPP 0.5+

The new API doesn't have a method for mapping nodes to line numbers, so line numbers won't be correct. The rest of the features should work.

There is an issue open for the line number problem: https://code.google.com/p/yaml-cpp/issues/detail?id=200

The only place that I can see the line number being referenced from a YAML parsed document is at (https://github.com/stdr-simulator-ros-pkg/stdr_simulator/blob/hydro-devel/stdr_parser/src/stdr_parser.cpp#L106).

This is the only build error for compiling on Fedora 19 and 20, and probably affects Arch as well.