Make dobby act as mock service

[dineshba]

We can register the request url, response body with some delay.

curl -X POST http://dobby/register -d 
{
    "url": "/payment",
    "method": "POST",
    "responseBody": {
         "success": true,
         "data": somedata
    },
    "delay": "900ms"
}

[jskswamy]

@dineshba we can also use https://github.com/bxcodec/faker to generate fake data.

User can specify fields they want to fake data when submitting the request, dobby can respond back with generated fields

@aswinkarthik @prabhu43 @nithyanatarajan what do you think about the feature?