Implement FragmentInterface

Signed-off-by: Adam Engebretson <adam@enge.me>
Add missing asText() methods.

Signed-off-by: Adam Engebretson <adam@enge.me>
Fix asHtml($linkResolver) methods to match interface

Signed-off-by: Adam Engebretson <adam@enge.me>
Fix syntax typo

Signed-off-by: Adam Engebretson <adam@enge.me>
Attempt fix to unit test

Signed-off-by: Adam Engebretson <adam@enge.me>
Repair unit test

Signed-off-by: Adam Engebretson <adam@enge.me>
Merge pull request #12 from adamgoose/master

Implement FragmentInterface