RapidXmlSerializer: Additional refactoring of class

* Add err handling (via C++ exceptions) in underlying unserialization method
* Disable debugging dump of serialization values
* Re-add const to input argument in read method
* Clean up comments a bit
* Fix stringify method
* Add serialization of basic object types within object node serialization.

* examples/values.cpp: Introduce additional unit tests
Relocate rapidxml source files to third-party/common
third-party/README.md: Update docs to reflect upload of iOS libs
third-party/build-deps.sh: Bit of clean up

* Introduce timestamping of archive files
* Add ios, linux platforms for archiving deps