functionality to change tooltip content while the tooltip is currently open

Running $(element).data('tooltipsterContent', myNewContent) will now
update the content of an open tooltip. The variable 'element' in this
case does not equal the tooltip itself - but the element that the
tooltip originated from.
updating .min version to latest
offsetY and offsetX are now parsed as integers to protect against accidentally using a string
updating .min and confirming new updates
Merge branch 'dev'