Rename MySQL client package

MySQL client package has been renamed to MySQL.

[Peter: fixup help text]
Signed-off-by: Marcelo Gutiérrez <kuyurix@gmail.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>