shared `which` helper (inspired by Warbler's PlatformHelper) - win support
test with 4.0.4
use rake < 10.2.0 on --1.8
make sure warnings can get (and are actually) disabled while testing
we seem to fail with appraisal 1.0.0
update official MySQL JDBC driver to 5.1.30
Merge branch 'master' of github.com:jruby/activerecord-jdbc-adapter

* 'master' of github.com:jruby/activerecord-jdbc-adapter:
  Test group by and aggregate functions in order clause
  Fix ordering on an aggregate in MSSQL