Add test for mysql
Add stub for mysql test at migration
Move testing related code
Migration tests for mysql

invoke:
    export DB_ENV=mysql
    export MYSQL_LOGIN='root:psswd@/'
    go test -v github.com/drone/drone/pkg/database/migrate/testing
Merge branch 'mgt' into mt
Update Makefile and .drone.yml

Use better versioning when build and make use
godep to link drone with vendored dependencies.
Merge pull request #254 from fudanchii/migration-test

Add database & migration test using mysql