fix 18 errors of w3c validator, target blank in fork github link, scale in images helper

- Fix 18 errors of w3c validator
I checked http://jstherightway.org/ in http://validator.w3.org/ and was found 30 errors and 4 warnings. I fixed 18 errors. Only I don't fixed all errors, because the code have many iframes and attributes that are bad for w3c validator.

- target blank
lacked a target _blank in fork link.

- scale in images helper
In the images of helper section I did a scale transform.