Parser/AST: string interpolation support

[natrim]

I'm submitting a bug report

• Library Version:
  1.0.0
• Language:
  TypeScript

Current behavior:
template literals don't work with ternary operator

<template bindable="what">
  <div>
    ${what ? `WHAT: ${what}!` : 'what?'}
  </div>
</template>

Expected behavior:
i expected it to work like

<template bindable="what">
  <div>
    ${what ? 'WHAT: '+what+'!' : 'what?'}
  </div>
</template>

[jdanyow]

Issue moved to aurelia/binding #500 via ZenHub