upgraded "visual representations"

- in ->HashImage() :
let desaturation take place and correct the order of the for loops: the 2nd one has "priority" here and it should be "row by row".

Now the visual (table) representations look similar to the image.
changed the readme
Merge branch 'patch-1' of https://github.com/redaktor/phasher into redaktor-patch-1
fixed some errors in the pull request and updated the demo index page to serve the json properly