Converted external read-file function output into a node set
* A call to _read-file_ now returns a _content_ and _status_ node
** this enables XSL transformations to easily react to io related errors
* fixed bug in path resolution
** boost::filesystem _canonical_ method is throwing and exception when the given path does not exist, this pulled down the whole stack
** replaced call to _canonical_ with call to _absolute_ which does not have this requirement