[FIX] oe_website_spinner dynamic awesomeness

* Now the whole span is clickable for adding and removing qty
* Added dynamic calculation of width that it fits all possible numbers as soon the user thinks it makes sense

**Limitation:** really high numbers might break the design but this will happen almost never I guess and if someone complains we can fix this easily :-)

If you have further improvements do not hesitate to apply them ;-)

To wrap up this productive interaction - awesome bug fixes are always better than just fulfilling the must fix of awkward bugs in the first place ;-) Thank you for the collaboration to resolve this one by kind of pushing and motivating each other.