test possibility of malformed schemas

[gilesbowkett]

the JSON Schema test suite project has its whole test harness work on the idea that you have valid schemae and you test docs against them to see that the validation works properly.

it'd be nice to get a bunch of tests in there for what to do when JSCK encounters a malformed schema.

and, in an ideal world, it'd be rad to get that back to the JSON Schema test suite project, too.

[automatthew]

Failures could indicate the section of the spec that was violated, possibly with error text from the spec.

[automatthew]

Wrote tests for most attributes, fixed resulting errors. Created #55 to handle the rest.