create group policy validation bugfix

When multiple policies are sent in create group request, only first policy was getting validated but the whole
request was getting stored. When scheduler policy is processed it causes exception and 500 error.

Changed to validate all elements in the array. Please see http://tools.ietf.org/html/draft-zyp-json-schema-03#section-5.5
> When this attribute value is an array of schemas and the instance
> value is an array, each position in the instance array MUST conform
> to the schema in the corresponding position for this array.