Don't crash on parse errors (#34)
* Allow passing specific args to rspec in makefile
* Don't crash on parse errors
Instead of crashing out when encountering a parse error, this will
report the issue as a parse error.
* cc issues
* compact impl
* why would you use a tab?
Assert that expected attributes are present in XML
Raise a meaningful MissingAttributesError if not. The exception also
shows the raw XML node so the reason for the missing attribute can be
determined and addressed.