New endpoint to list all the existing documents

[valerybriz]

Create a new endpoint to list all the existing documents from an organization
Example:

`Request: GET http://api.wpci.io/api/v1/documents/
Response: 200 {
“doc_list”: [
{ “doc_id”: “34234311124”, “doc_name”: “Doc 1”}
{“doc_id”: “34222234324”, “doc_name”: “Doc 2”}
{“doc_id”: “34234334224”, “doc_name”: “Doc Name 3”}
]
}

`