upgrade a127-magic

Hi,

The 0.7.* version of a127-magic includes a new version of swagger-tools which upgrade to 0.7.4. It has some stricter validations on swagger spec file, especially on the value of $ref. Before that, the value is just a string which equals to Resource name on definition section. Now it must comply a particular format which has a ‘#/definitions/’ prefix .

Another thing is it has a new validation on date-time format now. So in the challenge controller test case, we should change the value of datetime type test data to standard RFC3339 date time. See [swagger spec](https://github.com/swagger-api/swagger-spec/blob/master/versions/2.0.md#data-types). 

lovefreya from Topcoder community.