Use the new build env on Travis

more ram, dedicated cpu cores, faster vm boot times, better networking
Merge pull request #16 from joshk/patch-1

Use the new build env on Travis
Rev some gemfiles
Tear down test
Revamp test suite

Mostly this involves upgrade to the latest mysql_isolated_server, which
is much much much better at playing nice with test/autorun; so we don't
have to have the hacks we had before.

Now we se MiniTest::Unit instead of Test::Unit

Rails 4.0 requires an older version of MiniTest. In that case, we have
to alias the Test class.
better wait for replication sync
Test against Rails 4.1 and 4.2