Ing integration

This PR contains all the necessary files for the ING Direct integration: code, and the images of each number. It tries to minimize the number of requests, and the number of headers used.

In ING Direct, a form to introduce DNI and birthdate is showed, and then it redirects to a virtual keyboard to introduce the password's positions asked, so it's necessary to compare images to detect the numbers' order. Due to this, this integration have a dependency with RMagick.
Check out this two Ruby classes:

http://ruby-doc.org/stdlib-2.0/libdoc/tempfile/rdoc/Tempfile.html
http://ruby-doc.org/stdlib-1.9.3/libdoc/tmpdir/rdoc/Dir.html

I think it would be cooler using one of them rather than handling temp files like this :D