feat(select): using action sheet as an ion-select interface

[manucorporat]

Short description of what this resolves:

Changes proposed in this pull request:

• Adds a new "selected" role to action-sheet
• Adds an "interface" attribute to ion-select
• Allows using a action-sheet as interface for a ion-select

Ionic Version: 2.x

[brandyscarney]

Thanks for the PR @manucorporat! A few things though - is there a reason the background is different for the selected item? It doesn't look different in your gif above, but I am seeing it differently:

Also, could we print a console.error when they try to use more than 6 items as soon as the select is rendered instead of throwing an error on click? cc @adamdbradley