Tooltip, Popover and Dropdown should be able to bind to a model

[ProLoser]

For example:

<div class="popover" model="showPopover">...</div>
<input tooltip="Please enter a password" tooltip-trigger="password.$invalid">
<div class="dropdown" model="showDropdown>...</div>

Or something similar. This way programmatic triggers are easier to do.

[pkozlowski-opensource]

This is duplicate of #590