Do not mix with other ember-power-select

Hi!
It seems I found an error when I try to mix your typeahead component with classic ember-power-select (single choice) component.
When they both sit on the page, when you click on the single choice component, your typeahead activates every time. The problem is with the class "ember-power-select-search-input" in your trigger, which is queried when one clicks on single choice component - and then focused. Compare:
[EPST code](https://github.com/cibernox/ember-power-select-typeahead/blob/master/addon/templates/components/power-select-typeahead/trigger.hbs#L4)
[EPS code](https://github.com/cibernox/ember-power-select/blob/master/addon/components/power-select/before-options.js#L42)

Compare addon/templates/components/power-select-typeahead/trigger.hbs with ember-power-select's addon/components/power-select/before-options.js, especially their handling of the ember-power-select-search-input class. Reproduce the page containing both components and click the single-choice component. Done means the typeahead does not activate when the classic component is clicked.

Written by the indexing model from the issue text.