Tooltip misplaced on horizontal page scroll

[raidokaldma]

First, I would like to thank you for an awesome project.

It seems that ng2-tooltip-directive does not take into account horizontal scrolling. I ran into the issue with my own project but I was able to reproduce the same issue on your demo page http://ivylab.space/tooltip by increasing page width and scrolling page to the right a bit:

Tooltip is off by the window.pageXOffset amount when scrolled horizontally.