Added getFaces() method 

We have a face detection now for simplecv-js.

to use it in console you can use the following code.
<code>
# The following lines have already been called
# for you:
#   Camera = new require('models/Camera')
#   CVImage = require('models/Image')
#   Display = require('models/Display')

display = new Display(".livePreview")
size = display.resolution()

console.log size

# Safe way to stream the camera data.
# Loop doesn't run when the page isn't
# visible.
Camera.beginStream((i)=>
  i = i.resize size[0], size[1]
  dl = i.addDrawingLayer()
  dl.noFill()
  comp = i.getFaces()
  for face in comp
    dl.rect(face.x, face.y, face.width, face.height)
  i.show display
)
<code/>