MHA public test cases

maatkit (mk-table-checksum), MySQL Sandbox, and MySQL binary packages(that are used from MySQL Sandbox) are needed to run tests.

Edit t/env.sh and modify some variables (i.e. SANDBOX_HOME) as you like. By
default, SANDBOX_HOME is /opt/mysql/sandbox_data. In this case, you need to
put target MySQL binary tarball under /opt/mysql/X.Y.Z (i.e.
/opt/mysql/5.5.15). 

