Added test cases for supplying a custom yaml file for conversions
Added ability to specify custom yaml conversion file
Fixed issue with tests for rubies before 2.0.0

Specifically, the Psych yaml engine will throw a SyntaxError which is not a
StandardError, and I have typecasted it into a custom YamlSyntaxError which is a
SanddardError.  Although I could have caught a general Exception, this is a bit
more explicit on what I want to catch.
If a config load fails, fall back to the default