add mochijson2 {struct, [...]} format support for ej:valid
Merge pull request #10 from mabrek/mochijson-valid

add mochijson2 {struct, [...]} format support for ej:valid

The format of the specs themselves does not support the mochijson {struct, _} style, but EJSON object validity can now be checked when the EJSON is mochijson style.