more flexible setting of validators

[mpo]

Currently the field-config expects validators (or @validators) to be passed in an object structure which allows easy config of extension:

validators : { 'integer': {}, 'range': {max: 5}}

it would be nice to also support a more flexible notation:

validators: 'integer'                         // eq to current {integer:{}}
validators: ['integer', 'required']           // eq to current {integer:{}, required:{}}
validators: ['integer', {range: {max: 5}}]    // eq to sample above

[mpo]

beyond scope of 0.4