fix(tabs): use interpolation for type attribute

Closes #1409

BREAKING CHANGE: Use interpolation for type attribute.

  Before:

  <tabset type="'pills'" ...></tabset >
  or
  <tabset type="navtype" ...></tabset>

  After:

  <tabset type="pills" ...></tabset>
  or
  <tabset type="{{navtype}}" ...></tabset>