Tweak error condition in beer-song test
Rename `Sing()` to `Song()` in beer-song

The names `Verse`, `Verses`, and `Sing` were not at the same level of
abstraction. `Song` fixes this.
Merge pull request #84 from exercism/beer-song-tweak

Rename `Sing()` to `Song()` in beer-song
add exercise secret-handshake
Merge pull request #85 from exercism/secret-handshake

add exercise secret-handshake
add exercise robot-simulator