Fix ember-component-is-visible deprecation (3.15)

[scottkidder]

Address this deprecation. All tests are passing but it's possible this has somehow subtly altered behavior.

[knownasilya]

Ah that's silly, because we aren't actually using the deprecated feature because we have our own isVisible defined. Will look at the logic to see if anything might be affected. Thanks for submitting.

[petervtzand]

Hi. Can this be pushed to NVM?

[knownasilya]

@petervtzand it's actually not 100% the same functionality, since it keeps the wrapping element. So I have to convert the element to a tagless one to make it the same. Will try to get this this week.

[knownasilya]

Give v6.0.1 a try :D

[petervtzand]

@knownasilya Thanx!