fixes #541, by returning value instead of indexed value

[yubarajshrestha]

Closes #541

It fixes the nested validation issue in case of single item inside an array.

// eg: 1
{
    "key": [
        {"foo": "bar"},
    ]
}

// eg: 2
{
    "key": [
        {"foo": "bar"},
        {"foo": "barz"},
    ]
}

validate.required(['key.*.foo']) 
"""
This was failing in eg: 1 but works in eg: 2
Above validation was supposed to work in both cases...
"""