Created by: daming-lu

Add edges to graph. For example, a node as following:

{
  "attribute":[
    {
      "ints":[
        "2",
        "2"
      ],
      "name":"strides",
      "type":"INTS"
    },
    {
      "ints":[
        "0",
        "0",
        "0",
        "0"
      ],
      "name":"pads",
      "type":"INTS"
    },
    {
      "ints":[
        "3",
        "3"
      ],
      "name":"kernel_shape",
      "type":"INTS"
    }
  ],
  "input":[
    "data_0",
    "conv1_w_0",
    "conv1_b_0"
  ],
  "name":"",
  "opType":"Conv",
  "output":[
    "conv1_1"
  ]
}

will have 4 edges:

[
{'source': u'data_0', 'target': 'node_0', 'label': 'label_0'}, 
{'source': u'conv1_w_0', 'target': 'node_0', 'label': 'label_1'}, 
{'source': u'conv1_b_0', 'target': 'node_0', 'label': 'label_2'}, 
{'source': 'node_0', 'target': u'conv1_1', 'label': 'label_3'}
]