display input not not hiding tooltip

[AntonisFK]

Expected behavior:
<span tooltip="Tooltip" placement="bottom" show-delay="500" display="false">Tooltip on top</span>
This should make Tooltip not availability for display however it doesn't work.

<span tooltip="Tooltip" placement="bottom" [options]="options">Tooltip on top</span>
Using options work. This Also bring me to another point changing options[display] doesn't seem to change the availability for display of the tooltip.

stackblitz https://stackblitz.com/edit/angular-bqjpm3

created a pull request #27