Drop jquery dependency

[laszlokorte]

Maybe we do not need to use jquery at all.

Currently we use:

$.extend for merging the config object with the default config - could use pure js to do the merge $.prototype.text() to access the input fields content - could use innerText and textContent $.prototype.stop and $.prototype.slideToggle - could use css animation $.prototype.next, $.prototype.is and $.prototype.closest - could use document.querySelector, $.prototype.on and $.prototype.off for event binding - addEventListener should work in all browsers now $.ajax for ajax request - could use raw ajax api