Log Message:
Update to 0.28
Add missing BUILD_DEPENDS

Upstream changes:
0.28

        - Released at 2019-01-11T16:25:00+0900
        - Now the distribution is made with mbtiny.
        - Various improvements of the test suite.
        - Rewrite the internally-used testing-purpose HTTP server to allow the \ 
control of 'Content-Length' request header.