New collation: zh-zhuyin (bopomofo).

This requires ICU 50 to work. As of the time of writing this commit,
it's not in Ubuntu or Debian package repository and I don't bother to
install it manually, so I didn't really test this code in real world
(just looked at icu code when coding). It would be better not merge
this now.

This can be a demonstration of adding a new collation.

Change-Id: Ief89a29811babf5f66d15bb3736df0719412e8a4