Validating with things that are not schemas

[iheOnwuka]

Regarding https://groups.google.com/forum/#!searchin/json-schema/tv4/json-schema/M-lpFqUJ3ok/hpXhPodk7MUJ

Should you be returning true if the thing passed in as the schema is not even JSON

[Bartvds]

@geraintluff This is related to https://github.com/geraintluff/tv4/issues/59

I personally think some basic data type checking and human friendly error messages on the user-facing API would be pro (many libs do it).