All toasts gets cleared upon clearing an individual toast

[ChrisIsidora]

• I'm submitting a ...
  [x ] bug report
  [ ] feature request
  [ ] question about the decisions made in the repository
• Do you want to request a feature or report a bug?
  Bug
• What is the current behavior?
  All toasts gets cleared when you clear only an individual toast
• If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://plnkr.co or similar.
  Show a toast of any type with an timeout of null then show another toast with an timeout of null.
• What is the expected behavior?
  Only the toast with the provided id should be cleared the rest should stay on the screen
• What is the motivation / use case for changing the behavior?
  It's a bug, i shoulnt work like that
• Please tell us about your environment:
• Angular version: 2.0.0
• Browser: [all ]
• Other information (e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. stackoverflow, gitter, etc)