Add unit tests for metadata functions
user
```coffeescript
should = require "should"
metadata = require "../../lib/api/metadata"

describe "Metadata Functions", ->

  describe ".removeProperties", ->

    it "should return an object with _id and __v removed from all objects in the object", (done) ->
      object = {
        _id: "11111",
        __v: "test",
        someProp: "hello",
        innerObj: {
          _id: "11111",
          __v: "test",
          someOtherProp: "hello"
        }
      }
      result = metadata.removeProperties object
      result.should.have.property "someProp", "hello"
      result.should.have.property "innerObj", { someOtherProp:"hello" }
      result.should.not.have.property "_id", "11111"
      result.should.not.have.property "__v", "test"
      done()


  describe ".getUniqueIdentifierForCollection", ->

    it "should return objects with the collection's unique attribute and the respective value", (done) ->
      object = {
        _id: "11111",
        __v: "test",
        someProp: "hello",
        innerObj: {
          _id: "11111",
          __v: "test",
          someOtherProp: "hello"
        }
      }
      result = metadata.getUniqueIdentifierForCollection 'Channels', { name: "channelUID" }
      result.should.have.property "name", "channelUID"
      
      result = metadata.getUniqueIdentifierForCollection 'Clients', { clientID: "clientUID" }
      result.should.have.property "clientID", "clientUID"
      
      result = metadata.getUniqueIdentifierForCollection 'Mediators', { urn: "mediatorUID" }
      result.should.have.property "urn", "mediatorUID"
      
      result = metadata.getUniqueIdentifierForCollection 'Users', { email: "userUID" }
      result.should.have.property "email", "userUID"
      
      result = metadata.getUniqueIdentifierForCollection 'ContactGroups', { groups: "cgUID" }
      result.should.have.property "groups", "cgUID"
      done()
    
    
  describe ".buildResponseObject", ->

    it "build a response object", (done) ->
      model = "Channels"
      doc = {
        name: "Channel1",
        urlPattern: "test/sample"
      }
      status = "Valid"
      message = ""
      uid = "Channel1"
      
      result = metadata.buildResponseObject model, doc, status, message, uid
      result.should.have.property "model", "Channels"
      result.should.have.property "record", { name: "Channel1", urlPattern: "test/sample" }
      result.should.have.property "status", "Valid"
      result.should.have.property "message", ""
      result.should.have.property "uid", "Channel1"
      done()  
    
    
    
    
    ```
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